Atmospheric electricity - AbsoluteAstronomy.com

Atmospheric electricity is the regular diurnal

Diurnal phase shift

In telecommunication, diurnal phase shift is the phase shift of electromagnetic signals associated with daily changes in the ionosphere. The major changes usually occur during the period of time when sunrise or sunset is present at critical points along the path. Significant phase shifts may occur...

variations of the Earth's atmospheric electromagnetic

Electromagnetism

Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...

network

Electrical network

An electrical network is an interconnection of electrical elements such as resistors, inductors, capacitors, transmission lines, voltage sources, current sources and switches. An electrical circuit is a special type of network, one that has a closed loop giving a return path for the current...

(or, more broadly, any planet's electrical system in its layer of gases

Atmosphere

An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

). The Earth's surface, the ionosphere

Ionosphere

The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere...

, and the atmosphere is known as the global atmospheric electrical circuit. Atmospheric electricity is a multidisciplinary topic.

There is always free electricity in the air and in the clouds, which acts by induction

Electrostatic induction

Electrostatic induction is a redistribution of electrical charge in an object, caused by the influence of nearby charges. Induction was discovered by British scientist John Canton in 1753 and Swedish professor Johan Carl Wilcke in 1762. Electrostatic generators, such as the Wimshurst machine, the...

on the earth and electromagnetic devices. Experiments have shown that there is always free electricity in the atmosphere, which is sometimes negative and sometimes positive, but most generally positive, and the intensity of this free electricity is greater in the middle of the day than at morning or night and is greater in winter than in summer. In fine weather, the potential

Electric potential

In classical electromagnetism, the electric potential at a point within a defined space is equal to the electric potential energy at that location divided by the charge there...

increases with altitude

Altitude

Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...

at about 30 volt

Volt

The volt is the SI derived unit for electric potential, electric potential difference, and electromotive force. The volt is named in honor of the Italian physicist Alessandro Volta , who invented the voltaic pile, possibly the first chemical battery.- Definition :A single volt is defined as the...

s per foot (100 V/m).

The atmospheric medium, by which we are surrounded, contains not only combined electricity, like every other form of matter, but also a considerable quantity in a free and uncombined state; sometimes of one kind, sometimes of the other; but as a general rule it is always of an opposite kind to that of the Earth. Different layers, or strata, of the atmosphere, located at only small distances from each other, are frequently found to be in different electric states. The phenomena of atmospheric electricity are of three kinds. There are the electrical phenomena of thunderstorm

Thunderstorm

A thunderstorm, also known as an electrical storm, a lightning storm, thundershower or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically assigned cloud type associated with the...

s and there are the phenomena of continual electrification in the air. The phenomena of the polar

Polar region

Earth's polar regions are the areas of the globe surrounding the poles also known as frigid zones. The North Pole and South Pole being the centers, these regions are dominated by the polar ice caps, resting respectively on the Arctic Ocean and the continent of Antarctica...

auroras

Aurora (astronomy)

An aurora is a natural light display in the sky particularly in the high latitude regions, caused by the collision of energetic charged particles with atoms in the high altitude atmosphere...

constitute a third branch of the subject.

Most authorities are agreed, however, that whatever may be the origin of free electricity in the atmosphere, the electricity of enormous voltages that disrupts the air and produces the phenomena of lightning

Lightning

Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...

is due to the condensation

Condensation

Condensation is the change of the physical state of matter from gaseous phase into liquid phase, and is the reverse of vaporization. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition....

of the watery vapor forming the clouds; each minute drop, as it moves through the air, collects upon its surface a certain amount of free electricity. Then, as these tiny drops coalesce into larger drops, with a corresponding decrease in the relative surface exposed, the electric potential rises until it overcomes the resisting

Electrical resistance

The electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...

power of the air. This remark will be more clearly understood when it is considered that, with a given charge of electricity, an object's potential rises as the electrical capacity

Capacitance

In electromagnetism and electronics, capacitance is the ability of a capacitor to store energy in an electric field. Capacitance is also a measure of the amount of electric potential energy stored for a given electric potential. A common form of energy storage device is a parallel-plate capacitor...

of the object holding the charge is decreased, which is the case when the minute drops coalesce into larger drops. The similarity of lightning to the electricity developed by an electrical machine

Electrostatic generator

An electrostatic generator, or electrostatic machine, is a mechanical device that produces static electricity, or electricity at high voltage and low continuous current...

was demonstrated by Franklin

Benjamin Franklin

Dr. Benjamin Franklin was one of the Founding Fathers of the United States. A noted polymath, Franklin was a leading author, printer, political theorist, politician, postmaster, scientist, musician, inventor, satirist, civic activist, statesman, and diplomat...

in his memorable kite experiments.

History

The detonating sparks

Electric spark

An electric spark is a type of electrostatic discharge that occurs when an electric field creates an ionized electrically conductive channel in air producing a brief emission of light and sound. A spark is formed when the electric field strength exceeds the dielectric field strength of air...

drawn from electrical machines and from Leyden jar

Leyden jar

A Leyden jar, or Leiden jar, is a device that "stores" static electricity between two electrodes on the inside and outside of a jar. It was invented independently by German cleric Ewald Georg von Kleist on 11 October 1745 and by Dutch scientist Pieter van Musschenbroek of Leiden in 1745–1746. The...

s suggested to the early experimenters, Hauksbee, Newton

Isaac Newton

Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...

, Wall, Nollet

Jean-Antoine Nollet

Jean-Antoine Nollet was a French clergyman and physicist. As a priest, he was also known as Abbé Nollet. He was particularly interested in the new science of electricity, which he explored with the help of Du Fay and Réaumur...

, and Gray

Stephen Gray (scientist)

Stephen Gray was an English dyer and amateur astronomer, who was the first to systematically experiment with electrical conduction, rather than simple generation of static charges and investigations of the static phenomena....

, that lightning and thunder

Thunder

Thunder is the sound made by lightning. Depending on the nature of the lightning and distance of the listener, thunder can range from a sharp, loud crack to a long, low rumble . The sudden increase in pressure and temperature from lightning produces rapid expansion of the air surrounding and within...

were due to electric discharges. In 1708, Dr. William Wall

William Wall (theologian)

William Wall was a British priest in the Church of England who wrote extensively on the doctrine of infant baptism. He was generally an apologist for the English church and sought to maintain peace between it and the Anabaptists.He was born in Kent, got his BA from Queen's College, Oxford in 1667...

was one of the first to observe that spark discharges resembled miniature lightning, after observing the sparks from a charged piece of amber

Amber

Amber is fossilized tree resin , which has been appreciated for its color and natural beauty since Neolithic times. Amber is used as an ingredient in perfumes, as a healing agent in folk medicine, and as jewelry. There are five classes of amber, defined on the basis of their chemical constituents...

.

In the middle of the 18th century, Benjamin Franklin's experiments showed that electrical phenomena

Electrical phenomena

Electrical phenomena are commonplace and unusual events that can be observed which illuminate the principles of the physics of electricity and are explained by them.Electrical phenomena are a somewhat arbitrary division ofelectromagnetic phenomena....

of the atmosphere were not fundamentally different from those produced in the laboratory

Laboratory

A laboratory is a facility that provides controlled conditions in which scientific research, experiments, and measurement may be performed. The title of laboratory is also used for certain other facilities where the processes or equipment used are similar to those in scientific laboratories...

. By 1749, Franklin observed lightning to possess almost all the properties observable in electrical machines.

In July 1750, Franklin hypothesized that electricity could be taken from clouds via a tall metal aerial

Antenna (radio)

An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...

with a sharp point. Before Franklin could carry out his experiment, in 1752 Thomas-François Dalibard

Thomas-François Dalibard

Thomas-François Dalibard was born in Crannes-en-Champagne, France in 1709 and died in 1799.-Relationship with Ben Franklin:He first met U.S. scientist Benjamin Franklin in 1767 during one of Franklin's visits to France and it is said that they became friends.In 1750, Benjamin Franklin published a...

erected a 40 feet (12.2 m) iron

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

rod at Marly-la-Ville

Marly-la-Ville

Marly-la-Ville is a commune in the Val-d'Oise department in Île-de-France in northern France.-References:** -External links:* * *...

, near Paris, drawing sparks from a passing cloud. With ground

Ground (electricity)

In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth....

-insulated aerials, an experimenter could bring a grounded lead with an insulated wax handle close to the aerial, and observe a spark discharge from the aerial to the grounding wire. In May of 1752, Dalibard affirmed that Franklin's theory was correct.

Franklin listed the following similarities between electricity and lightning:

producing light of a similar color;
rapid motion;
being conducted
Electrical conductor
In physics and electrical engineering, a conductor is a material which contains movable electric charges. In metallic conductors such as copper or aluminum, the movable charged particles are electrons...

by metals, water and ice;
melting metals and igniting
Making fire
Fire was an essential tool in early human cultural development and still important today. Many different techniques for making fire exist...

inflammable
Flammability
Flammability is defined as how easily something will burn or ignite, causing fire or combustion. The degree of difficulty required to cause the combustion of a substance is quantified through fire testing. Internationally, a variety of test protocols exist to quantify flammability...

substances;
"sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

ous" smell (which is now known to be due to ozone
Ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...

);
magnetizing needles;
the similarity between St. Elmo's Fire
St. Elmo's fire
St. Elmo's fire is a weather phenomenon in which luminous plasma is created by a coronal discharge from a grounded object in an electric field in the atmosphere St. Elmo's fire is named after St. Erasmus of Formiae St. Elmo's fire (also St. Elmo's light) is a weather phenomenon in which luminous...

and glow discharge
Electric glow discharge
An electric glow discharge is a plasma formed by the passage of current at 100 V to several kV through a gas, often argon or another noble gas. It is found in products such as neon lamps and plasma-screen televisions, and is used in plasma physics and analytical chemistry.-Basic operating...

.

Around June of 1752, Franklin reportedly performed his famous kite experiment. The kite experiment was repeated by Romas, who drew from a metallic string sparks 9 feet (2.7 m) long, and by Cavallo

Tiberius Cavallo

Tiberius Cavallo was an Italian physicist and natural philosopher.-Life:He was born at Naples, where his father was a physician....

, who made many important observations on atmospheric electricity. L. G. Lemonnier (1752) also reproduced Franklin's experiment with an aerial, but substituted the ground wire with some dust particles (testing attraction). He went on to document the fair weather condition
Fair weather condition
Fair weather condition concerns the electric field and the electric current in the air as well as the conductivity of the atmosphere. It is the electrostatic longitudinal modes and electromagnetic transverse mode or state of different meteorological conditions, concerning measurements of...

, the clear-day electrification of the atmosphere, and the diurnal

Diurnal phase shift

variation of the atmosphere's electricity. G. Beccaria

Giovanni Battista Beccaria

Giovanni Battista Beccaria , Italian physicist, was born at Mondovì, and entered the religious order of the Pious Schools in 1732, where he studied, and afterward taught, grammar and rhetoric...

(1775) confirmed Lemonnier's diurnal variation data and determined that the atmosphere's charge polarity

Electrical polarity

Electrical polarity is present in every electrical circuit. Electrons flow from the negative pole to the positive pole. In a direct current circuit, one pole is always negative, the other pole is always positive and the electrons flow in one direction only...

was positive in fair weather. H. B. Saussure

Horace-Bénédict de Saussure

200px|thumb|Portrait of Horace-Bénédict de Saussure Horace-Bénédict de Saussure was a Genevan aristocrat, physicist and Alpine traveller, often considered the founder of alpinism, and considered to be the first person to build a successful solar oven.-Life and work:Saussure was born in Conches,...

(1779) recorded data relating to a conductor's induced charge in the atmosphere. Saussure's instrument (which contained two small spheres suspended in parallel with two thin wires) was a precursor to the electrometer

Electrometer

An electrometer is an electrical instrument for measuring electric charge or electrical potential difference. There are many different types, ranging from historical hand-made mechanical instruments to high-precision electronic devices...

. Saussure found that the fair weather condition had an annual variation, and found that there was a variation with height, as well. In 1785, Coulomb

Charles-Augustin de Coulomb

Charles-Augustin de Coulomb was a French physicist. He is best known for developing Coulomb's law, the definition of the electrostatic force of attraction and repulsion. The [SI unit] of charge, the coulomb, was named after him....

discovered the electrical conductivity of air. His discovery was contrary to the prevailing thought at the time, that the atmospheric gases were insulators (which they are to some extent, or at least not very good conductors when not ionized

Ionization

Ionization is the process of converting an atom or molecule into an ion by adding or removing charged particles such as electrons or other ions. This is often confused with dissociation. A substance may dissociate without necessarily producing ions. As an example, the molecules of table sugar...

). His research was, unfortunately, completely ignored. P. Erman

Paul Erman

Paul Erman was a German physicist from Berlin, Brandenburg. He was the son of the historian Jean Pierre Erman , author of Histoire des refugis....

(1804) theorized that the Earth was negatively charged. J. C. A. Peltier

Jean Charles Athanase Peltier

Jean Charles Athanase Peltier ]] – October 27, 1845, in Paris) was a French physicist.He discovered the calorific effect of electric current passing through the junction of two different metals...

(1842) tested and confirmed Erman's idea. Lord Kelvin (1860s) proposed that atmospheric positive charges explained the fair weather condition and, later, recognized the existence of atmospheric electric field

Electric field

In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...

s.
Over the course of the next century, using the ideas of Alessandro Volta

Alessandro Volta

Count Alessandro Giuseppe Antonio Anastasio Gerolamo Umberto Volta was a Lombard physicist known especially for the invention of the battery in 1800.-Early life and works:...

and Francis Ronald, several researchers contributed to the growing body of knowledge about atmospheric electrical phenomena. With the invention of the portable electrometer and Lord Kelvin's 19th century water-dropping condenser

Kelvin water dropper

The Kelvin water dropper, invented by Lord Kelvin , is a type of electrostatic generator. Kelvin referred to the device as his water-dropping condenser...

, a greater level of precision was introduced into observational results. Towards the end of the 19th century came the discovery by W. Linss (1887) that even the most perfectly insulated conductors lose their charge, as Coulomb before him had found, and that this loss depended on atmospheric conditions. H. H. Hoffert (1888) identified individual lightning downward strokes using early cameras and would report this in "Intermittent Lightning-Flashes". J. Elster and H. F. Geitel, who also worked on thermionic emission

Thermionic emission

Thermionic emission is the heat-induced flow of charge carriers from a surface or over a potential-energy barrier. This occurs because the thermal energy given to the carrier overcomes the binding potential, also known as work function of the metal. The charge carriers can be electrons or ions, and...

, proposed a theory to explain thunderstorms' electrical structure (1885) and, later, discovered atmospheric radioactivity (1899). By then it had become clear that freely charged positive and negative ion

Ion

An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

s were always present in the atmosphere, and that radiant emanations could be collected. F. Pockels

Friedrich Carl Alwin Pockels

Friedrich Carl Alwin Pockels was a German physicist. He was born in Italy to Captain Theodore Pockels and Alwine Becker. He obtained a doctorate from the University of Göttingen in 1888, and from 1900 to 1913 he was professor of theoretical physics at the University of Heidelberg.In 1893 he...

(1897) estimated lightning current

Electric current

Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...

intensity by analyzing lightning flashes in basalt

Basalt

Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...

and studying the left-over magnetic field

Magnetic field

A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...

s (basalt, being a ferromagnetic mineral, becomes magnetically polarised when exposed to a large external field such as those generated in a lightning strike).

Using a Peltier electrometer
Electrometer
An electrometer is an electrical instrument for measuring electric charge or electrical potential difference. There are many different types, ranging from historical hand-made mechanical instruments to high-precision electronic devices...

, Luigi Palmieri

Luigi Palmieri

Luigi Palmieri was an Italian physicist and meteorologist. He was famous for his scientific studies of the eruptions of Mount Vesuvius, for his researches on earthquakes and meteorological phenomena and for improving the seismographer of the time.- Biography :Palmieri was born in Faicchio,...

researched atmospheric electricity. Nikola Tesla

Nikola Tesla

Nikola Tesla was a Serbian-American inventor, mechanical engineer, and electrical engineer...

and Hermann Plauson

Hermann Plauson

Hermann Plauson was an Estonian engineer and inventor. Plauson investigated the production of energy and power via atmospheric electricity.-Biography:...

investigated the production of energy

Energy

In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...

and power

Power (physics)

In physics, power is the rate at which energy is transferred, used, or transformed. For example, the rate at which a light bulb transforms electrical energy into heat and light is measured in watts—the more wattage, the more power, or equivalently the more electrical energy is used per unit...

via atmospheric electricity. Tesla also proposed to use the atmospheric electrical circuit to transmit energy wirelessly over large distances (see his Wardenclyffe Tower

Wardenclyffe Tower

Wardenclyffe Tower also known as the Tesla Tower, was an early wireless telecommunications tower designed by Nikola Tesla and intended for commercial trans-Atlantic wireless telephony, broadcasting, and to demonstrate the transmission of power without interconnecting wires...

and Magnifying Transmitter

Magnifying transmitter

The magnifying transmitter is an advanced version of Tesla coil transmitter. It is a high power harmonic oscillator that Nikola Tesla intended for the wireless transmission of electrical energy...

). The Polish Polar Station, Hornsund

Polish Polar Station, Hornsund

Polish Polar Station, Hornsund is at Isbjørnhamna in Hornsund fjord, on Spitsbergen island in the Norwegian Svalbard archipelago, operated since 1957.-Station:...

, has researched the magnitude of the Earth's electric field

Electric field

and recorded its vertical component. Discoveries about the electrification of the atmosphere via sensitive electrical instruments and ideas on how the Earth’s negative charge is maintained were developed mainly in the 20th century. Whilst a certain amount of observational work has been done in the branches of atmospheric electricity, the science has not developed to a considerable extent. It is thought that any apparatus which might be used to extract useful energy from atmospheric electricity would be prohibitively costly to build and maintain, which is probably why the field has not attracted much interest.

Description

Atmospheric electricity abounds in the environment; some traces of it are found less than four feet from the surface of the earth

Landform

A landform or physical feature in the earth sciences and geology sub-fields, comprises a geomorphological unit, and is largely defined by its surface form and location in the landscape, as part of the terrain, and as such, is typically an element of topography...

, but on attaining greater height it becomes more apparent. The main concept is that the air above the surface of the earth is usually, during fine weather, positively electrified, or at least that it is positive with respect to the Earth's surface, the Earth's surface being relatively negative

Electrical polarity

. Additionally, the presence of electrical action in the atmosphere, due to the accumulation of enormous static charges of current generated presumably by friction of the air upon itself, can account for the various phenomena of lightning and thunderstorm

Thunderstorm

s. Other causes to produce electricity in the atmosphere are, evaporation from the Earth's surface, chemical changes which take place upon the Earth's surface, and the expansion, condensation, and variation of temperature of the atmosphere and of the moisture contained in it.

According to M. Peltier, the terrestrial globe is completely negative, and inter-planetary space positive; the atmosphere itself has no electricity, and is only in a passive state; so that the effects observed are due to the relative influence of these two great stores of electricity. Researchers are disposed to assume that the terrestrial globe possesses, at least on its solid part, an excess of negative electricity, and that it is the same with bodies placed at its surface; but it appears to them to follow, from the various observations made, that the atmosphere itself is positively electrified. This positive electricity evidently arises from the same source as the negative of the globe. It is probable that it is essentially in the aqueous vapors with which the atmosphere is always more or less filled that it resides, rather than in the particles of the air itself; but it does not the less exist in the atmosphere.

The measurements of atmospheric electricity can be seen as measurements of difference of potential between a point of the Earth's surface, and a point somewhere in the air above it. The atmosphere in different regions is often found to be at different local potentials, which differ from that of the earth sometimes even by as much as 3000 Volts within 100 feet (30.5 m).
The electrostatic field and the difference of potential of the earth field according to investigations, is in summer about 60 to 100 volts and in winter 300 to 500 volts per meter of difference in height, a simple calculation gives the result that when such a collector is arranged for example on the ground, and a second one is mounted vertically over it at a distance of 2000 meters and both are connected by a conducting cable, there is a difference in potential in summer of about 2,000,000 volts and in winter even of 6,000,000 volts and more.

In the upper regions of the atmosphere the air is highly rarefied, and conducts like the rarefied gases in Geissler's tubes. The lower air is, when dry, a non-conductor. The upper stratum is believed to be charged with positive electricity, while the Earth's surface is itself negatively charged; the stratum of denser air between acting like the glass of a Leyden jar

Leyden jar

in keeping the opposite charges separate. The theory of atmospheric electricity explains equally many phenomena; free electricity, which is manifested during thunder-storms, being the cause of the former; and electricity of a lower tension, manifested during a display of the aurora borealis, causing the latter.

The electric atmosphere is the most frequent cause which deters or prevents electrical transmissions. During storms, it is seen that the some apparatus works irregularly, interrupting the passage of strong currents instantaneously, and often produces upon the apparatus in the offices, between metallic points, bright sparks; in telegraphic systems the armatures of the electro-magnets are drawn up with great force, and the wires and other metallic substances about the instruments fused. It is also observed, but more rarely, currents, which continue for a longer or shorter time, that prevent working of communication systems.

Variations

There have been various speculative conjectures regarding the origin of these semi-diurnal meteorological periods, but they have been usually of a secondary character. A primary cause is clearly to be ascribed to the many complex processes which are due to the thermodynamics of radiation. It is thought that with sufficient experience the formulas that have been deduced here, and illustrated, can be made to yield other valuable data regarding the atomic and subatomic activities which are concerned in the variations of the fundamental terms and their very numerous derivatives.

Diurnal variations found by the daily indications (during fine weather) showed two maxima occurring in summer at roughly twelve hours apart and two minima which in summer were at the hours of which were roughly nine hours apart. The maxima correspond fairly with hours of changing temperature, the minima with those of constant temperature. Atmospheric electricity, considered in a general manner, attains its maximum in January, then decreases progressively until the month of June, which presents a minimum of intensity; it increases during the following months to the end of the year. The difference between the maximum and minimum is much more sensibly felt during serene weather than during cloudy weather. During the different months, the electricity of the air is more powerful when the sky is serene than when it is cloudy, except toward the months of June and July, when the electricity attains a maximum, the value of which is nearly the same, whatever be the state of the sky.

The electric intensity observed during fogs has, at a mean, almost exactly the same value as that observed during snows. This value is very high, and corresponds to the mean maxima observed for the former and the latter months of the year. A very remarkable fact, which appears from recent observation, is that moisture acts in a manner altogether different in the cold months and in the hot ones; it increases the electricity in the winter months, it diminishes it in the summer months. The fundamental fact is, that humidity acts in two manners, the effects of which tend to oppose each other. On the one hand, it facilitates the escape of the electricity accumulated in the upper regions of the atmosphere to the stratum in which the observation is made; on the other hand, it facilitates the escape into the ground of the electricity which this stratum possesses: thus, on
the one hand it increases the intensity of the electric manifestations of the instrument, on the other hand it diminishes them.

Outer space and near space

In outer space, the magnetopause

Magnetopause

The magnetopause is the abrupt boundary between a magnetosphere and the surrounding plasma. For planetary science, the magnetopause is the boundary between the planet’s magnetic field and the solar wind. The location of the magnetopause is determined by the balance between the pressure of the...

flows along the boundary between the region around an astronomical object (called the "magnetosphere

Magnetosphere

A magnetosphere is formed when a stream of charged particles, such as the solar wind, interacts with and is deflected by the intrinsic magnetic field of a planet or similar body. Earth is surrounded by a magnetosphere, as are the other planets with intrinsic magnetic fields: Mercury, Jupiter,...

") and surrounding plasma, in which electric phenomena are dominated or organized by this magnetic field. Earth is surrounded by a magnetosphere, as are the magnetized planets Jupiter, Saturn, Uranus and Neptune. Mercury is magnetized, but too weakly to trap plasma. Mars has patchy surface magnetization. The magnetosphere is the location where the outward magnetic pressure of the Earth's magnetic field is counterbalanced by the solar wind

Solar wind

The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...

, a plasma. Most of the solar particles are deflected to either side of the magnetopause. However, some particles become trapped within the Earth's magnetic field and form radiation belts

Van Allen radiation belt

The Van Allen radiation belt is a torus of energetic charged particles around Earth, which is held in place by Earth's magnetic field. It is believed that most of the particles that form the belts come from solar wind, and other particles by cosmic rays. It is named after its discoverer, James...

. The Van Allen radiation belt

Van Allen radiation belt

is a torus of energetic charged particles (i.e. a plasma) around Earth, trapped by Earth's magnetic field.

At elevations above the clouds, atmospheric electricity forms a continuous and distinct element (called the electrosphere) in which the Earth is surrounded. The electrosphere layer (from tens of kilometers above the surface of the earth to the ionosphere) has a high electrical conductivity and is essentially at a constant electric potential. The ionosphere

Ionosphere

is the inner edge of the magnetosphere and is the part of the atmosphere that is ionized by solar radiation. (Photoionisation is a physical process in which a photon is incident on an atom, ion or molecule, resulting in the ejection of one or more electrons.)

Polar Aurora

The Earth is constantly immersed in the solar wind

Solar wind

, a rarefied flow of hot plasma (gas of free electrons and positive ions) emitted by the Sun in all directions, a result of the million-degree heat of the Sun's outermost layer, the solar corona

Corona

A corona is a type of plasma "atmosphere" of the Sun or other celestial body, extending millions of kilometers into space, most easily seen during a total solar eclipse, but also observable in a coronagraph...

. The solar wind usually reaches Earth with a velocity around 400 km/s, density around 5 ions/cc and magnetic field intensity around 2–5 nT (nanoteslas

Tesla (unit)

The tesla is the SI derived unit of magnetic field B . One tesla is equal to one weber per square meter, and it was defined in 1960 in honour of the inventor, physicist, and electrical engineer Nikola Tesla...

; Earth's surface field is typically 30,000–50,000 nT). These are typical values. During magnetic storms

Geomagnetic storm

A geomagnetic storm is a temporary disturbance of the Earth's magnetosphere caused by a disturbance in the interplanetary medium. A geomagnetic storm is a major component of space weather and provides the input for many other components of space weather...

, in particular, flows can be several times faster; the interplanetary magnetic field

Interplanetary Magnetic Field

The interplanetary magnetic field is the term for the solar magnetic field carried by the solar wind among the planets of the Solar System....

(IMF) may also be much stronger.

The IMF originates on the Sun, related to the field of sunspot

Sunspot

Sunspots are temporary phenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. They are caused by intense magnetic activity, which inhibits convection by an effect comparable to the eddy current brake, forming areas of reduced surface temperature....

s, and its field lines (lines of force)

Magnetism

Magnetism is a property of materials that respond at an atomic or subatomic level to an applied magnetic field. Ferromagnetism is the strongest and most familiar type of magnetism. It is responsible for the behavior of permanent magnets, which produce their own persistent magnetic fields, as well...

are dragged out by the solar wind. That alone would tend to line them up in the Sun-Earth direction, but the rotation of the Sun skews them (at Earth) by about 45 degrees, so that field lines passing Earth may actually start near the western edge ("limb") of the visible sun.

When the solar wind is perturbed, it easily transfers energy and material into the magnetosphere. The electrons and ions in the magnetosphere that are thus energized move along the magnetic field lines to the polar regions of the atmosphere.

Earth-Ionosphere cavity

Potential difference between the ionosphere

Ionosphere

and the Earth is maintained by thunderstorm

Thunderstorm

s' pumping action of lightning discharges. In the Earth-ionosphere cavity, the electric field

Electric field

and conduction current in the lower atmosphere are primarily controlled by ion

Ion

s. Ions have the characteristic parameters such as mobility

Electron mobility

In solid-state physics, the electron mobility characterizes how quickly an electron can move through a metal or semiconductor, when pulled by an electric field. In semiconductors, there is an analogous quantity for holes, called hole mobility...

, lifetime, and generation rate that vary with altitude

Altitude

.

The Schumann resonance

Schumann resonance

The Schumann resonances are a set of spectrum peaks in the extremely low frequency portion of the Earth's electromagnetic field spectrum...

is a set of spectrum peaks in the ELF portion of the Earth's electromagnetic field spectrum. Schumann resonance is due to the space between the surface of the Earth and the conductive ionosphere acting as a waveguide. The limited dimensions of the earth cause this waveguide to act as a resonant cavity for electromagnetic waves. The cavity is naturally excited by energy from lightning strikes.

Atmospheric layers

The electrical conductivity of the atmosphere increases exponentially with altitude

Altitude

. The amplitudes of the electric and magnetic components depend on season, latitude

Latitude

In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

, and height above the sea level. The greater the altitude the more atmospheric electricity abounds. The exosphere

Exosphere

The exosphere is the uppermost layer of Earth's atmosphere. In the exosphere, an upward travelling molecule moving fast enough to attain escape velocity can escape to space with a low chance of collisions; if it is moving below escape velocity it will be prevented from escaping from the celestial...

is the uppermost layer of the atmosphere and is estimated to be 500 km to 1000 km above the Earth's surface, and its upper boundary at about 10,000 km. The thermosphere

Thermosphere

The thermosphere is the biggest of all the layers of the Earth's atmosphere directly above the mesosphere and directly below the exosphere. Within this layer, ultraviolet radiation causes ionization. The International Space Station has a stable orbit within the middle of the thermosphere, between...

(upper atmosphere) is the layer of the Earth's atmosphere directly above the mesosphere and directly below the exosphere. Within this layer, ultraviolet radiation causes ionization. Theories that have been proposed to explain the phenomenon of the polar aurora, but it has been demonstrated by experiment

Experiment

An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...

s that it is due to currents of positive electricity passing from the higher regions of the atmosphere to the earth.

The mesosphere

Mesosphere

The mesosphere is the layer of the Earth's atmosphere that is directly above the stratosphere and directly below the thermosphere. In the mesosphere temperature decreases with increasing height. The upper boundary of the mesosphere is the mesopause, which can be the coldest naturally occurring...

(middle atmosphere) is the layer of the Earth's atmosphere that is directly above the stratosphere and directly below the thermosphere. The mesosphere is located about 50-80/85 km above Earth's surface. The stratosphere

Stratosphere

The stratosphere is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. It is stratified in temperature, with warmer layers higher up and cooler layers farther down. This is in contrast to the troposphere near the Earth's surface, which is cooler...

(middle atmosphere) is a layer of Earth's atmosphere that is stratified in temperature and is situated between about 10 km and 50 km altitude above the surface at moderate latitudes, while at the poles it starts at about 8 km altitude. The stratosphere sits directly above the troposphere and directly below the mesosphere. The troposphere

Troposphere

The troposphere is the lowest portion of Earth's atmosphere. It contains approximately 80% of the atmosphere's mass and 99% of its water vapor and aerosols....

(lower atmosphere) is the densest layer of the atmosphere.

The planetary boundary layer

Planetary boundary layer

The planetary boundary layer , also known as the atmospheric boundary layer , is the lowest part of the atmosphere and its behavior is directly influenced by its contact with a planetary surface. On Earth it usually responds to changes in surface forcing in an hour or less...

(PBL), also known as the atmospheric boundary layer (ABL), is the lowest part of the atmosphere and its behavior is directly influenced by its contact with the planetary surface. It is also known as the "exchange layer". (see also:p-n junction

P-n junction

A p–n junction is formed at the boundary between a P-type and N-type semiconductor created in a single crystal of semiconductor by doping, for example by ion implantation, diffusion of dopants, or by epitaxy .If two separate pieces of material were used, this would...

.)
There is a potential gradient

Potential gradient

A potential gradient is the local space rate of change of the potential with respect to displacement.In electrostatics then, it is the local space rate of change of the electric potential:Units are volts per meter...

at ground level ("Atmosphere ground layer") and this vertical field corresponds to the negative charge in and near the Earth's surface. The negative potential gradient falls rapidly as altitude increases from the ground. Most of this potential gradient is in the first few kilometers. The positive potential gradient rises rapidly as altitude increases from the ground. Volta, over two centuries before the 21st century, discovered with some degree of exactitude that the proportions of the ordinate

Ordinate

In mathematics, ordinate refers to that element of an ordered pair which is plotted on the vertical axis of a two-dimensional Cartesian coordinate system, as opposed to the abscissa...

s of the curve or gradient of electric potential increased as the distance from the earth increases, and, more recently, Engel has provided data to calculate the increase (Image to the right).

Thunderstorms and lightning

If the quantity of water that is condensed in and subsequently precipitated from a cloud is known, then the total energy of a thunderstorm can be calculated. In an average thunderstorm, the energy released amounts to about 10,000,000 kilowatt-hours (3.6 joule

Joule

The joule ; symbol J) is a derived unit of energy or work in the International System of Units. It is equal to the energy expended in applying a force of one newton through a distance of one metre , or in passing an electric current of one ampere through a resistance of one ohm for one second...

), which is equivalent to a 20-kiloton nuclear warhead

Nuclear weapon

A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...

. A large, severe thunderstorm might be 10 to 100 times more energetic.

How lightning initially forms is still a matter of debate: Scientists have studied root causes ranging from atmospheric perturbations (wind, humidity, and atmospheric pressure

Atmospheric pressure

Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...

) to the impact of solar wind

Solar wind

and accumulation of charged solar particles. Ice inside a cloud is thought to be a key element in lightning development, and may cause a forcible separation of positive and negative charge

Charge carrier

In physics, a charge carrier is a free particle carrying an electric charge, especially the particles that carry electric currents in electrical conductors. Examples are electrons and ions...

s within the cloud, thus assisting in the formation of lightning.

An average bolt of lightning carries a negative electric current of 40 kiloamperes (kA)

Ampere

The ampere , often shortened to amp, is the SI unit of electric current and is one of the seven SI base units. It is named after André-Marie Ampère , French mathematician and physicist, considered the father of electrodynamics...

(although some bolts can be up to 120 kA), and transfers a charge of five coulombs and 500 MJ

Joule

, or enough energy to power a 100-watt lightbulb for just under two months. The voltage depends on the length of the bolt, with the dielectric breakdown of air being three million volts per meter; this works out to approximately one gigavolt (one billion volts) for a 300 m (1000 ft) lightning bolt. With an electric current of 100 kA, this gives a power of 100 terawatts. However, lightning leader development is not a simple matter of dielectric breakdown, and the ambient electric fields required for lightning leader propagation can be a few orders of magnitude less than dielectric breakdown strength. Further, the potential gradient inside a well-developed return-stroke channel is on the order of hundreds of volts per meter or less due to intense channel ionization, resulting in a true power output on the order of megawatts per meter for a vigorous return-stroke current of 100 kA .

Electrification in the air

Electrostatics

Electrostatics is the branch of physics that deals with the phenomena and properties of stationary or slow-moving electric charges....

involves the buildup of charge on the surface of objects due to contact with other surfaces. Although charge exchange happens whenever any two surfaces contact and separate, the effects of charge exchange are usually only noticed when at least one of the surfaces has a high resistance to electrical flow. This is because the charges that transfer to or from the highly resistive surface are more or less trapped there for a long enough time for their effects to be observed. These charges then remain on the object until they either bleed off to ground or are quickly neutralized by a discharge: e.g., the familiar phenomenon of a static 'shock' is caused by the neutralization of charge built up in the body from contact with nonconductive surfaces.

St. Elmo's Fire
St. Elmo's fire
St. Elmo's fire is a weather phenomenon in which luminous plasma is created by a coronal discharge from a grounded object in an electric field in the atmosphere St. Elmo's fire is named after St. Erasmus of Formiae St. Elmo's fire (also St. Elmo's light) is a weather phenomenon in which luminous...

is a electrical phenomenon in which luminous plasma

Plasma (physics)

In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...

is created by a coronal discharge originating from a grounded object

Ground (electricity)

. Ball lightning

Ball lightning

Ball lightning is an unexplained atmospheric electrical phenomenon. The term refers to reports of luminous, usually spherical objects which vary from pea-sized to several metres in diameter. It is usually associated with thunderstorms, but lasts considerably longer than the split-second flash of a...

is often erroneously identified as St. Elmo's Fire. They are separate and distinct phenomena. Although referred to as "fire", St. Elmo's Fire is, in fact, plasma

Plasma (physics)

.
Saint Elmo's fire is another phase of atmospheric electricity to be considered in this connection. It is otherwise known as the fire of Saint Elias, of Saint Clara, of Saint Nicholas and of Helena, as well as composite, composant

Composant

In point-set topology, the composant of a point p in a continuum A is the union of all proper subcontinua of A that contain p. If a continuum is indecomposable, then its composants are pairwise disjoint. The composants of a continuum are dense in that continuum....

or corposant (that is, corpus sanctum [ed., holy body]). The phenomenon is observed, usually during a thunderstorm

Thunderstorm

, at the tops of trees, spires, etc., or on the heads of animals, as a brush or star of light.

The electric field around the object in question causes ionization

Ionization

of the air molecules, producing a faint glow

Ionized air glow

The ionized-air glow is the emission of characteristic blue–purple–violet light, of color called electric blue, by air subjected to an energy flux. -Processes:...

easily visible in low-light conditions. Approximately 1,000 – 30,000 volts per centimetre is required to induce St. Elmo's Fire; however, this number is greatly dependent on the geometry

Geometry

Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ....

of the object in question. Sharp points tend to require lower voltage levels to produce the same result because electric fields are more concentrated in areas of high curvature, thus discharges are more intense at the end of pointed objects. St. Elmo's Fire and normal sparks both can appear when high electrical voltage affects a gas. St. Elmo's fire is seen during thunderstorms when the ground below the storm is electrically charged, and there is high voltage in the air between the cloud and the ground. The voltage tears apart the air molecules and the gas begins to glow. The nitrogen and oxygen in the Earth's atmosphere causes St. Elmo's Fire to fluoresce with blue or violet light; this is similar to the mechanism that causes neon signs to glow.

Research and investigation

To detect the presence of free electricity in the air a pointed metal rod projecting into the air several feet and connected at its lower end to a gold leaf electroscope may be used. When this rod is projected into the air a few feet the leaves diverge. Kites and balloons have also been used to detect and, so to speak, draw down the free electricity of the air. The origin of atmospheric electricity is still unknown. Some physicists have ascribed it to the friction of the air upon the ground, others to the gradual oxidation of plant and animal life, others again to evaporation, to induction from the sun, and to differences of temperature.

Low altitude

For ascertaining the electric state of the atmosphere near the surface of the earth, Volta's electrometer is sufficient. An electrometer is an instrument which serves to indicate and measure electricity. The one just mentioned consists of a glass jar, surmounted by a pointed, metallic rod; and to the lower end of the rod, which enters the jar, two fine straws are loosely attached. The pointed rod, collecting the electricity from the air, the two straws become similarly electrified and recede from each other; the amount of divergence measuring the intensity of the fluid.

High altitude

Experiments are made in the higher regions of the atmosphere by the aid of kites and balloons. The string of the kite must be wound with fine wire, in order to convey the electricity from the sky; and it must also be insulated, by attaching the lower end either to a silken cord or glass pillar. Small, stationary balloons are sometimes employed, the strings of which are arranged and fastened in the same manner. Occasionally meteorologists ascend in balloons for the purpose of making observations.

Lightning

A lightning rocket

Lightning rocket

The term lightning rocket can generically describe a rocket device used to trigger lightning as well as a specific system patented by Robert E. Betts....

consists of a rocket launcher that is in communication with a detection device that measures the presence of electrostatic and ionic change in close proximity to the rocket launcher that also fires the rocket launcher. This system is designed to control the time and the location of a lightning strike.

External links

The Global Circuit, phys.uh.edu
Soaking in atmospheric electricity 'Fair weather' measurements important to understanding thunderstorms. science.nasa.gov
Atmospheric Electricity HomePage, uah.edu
Tjt, Fair-weather atmospheric electricity. ava.fmi.fi
ICAE – International Commission on Atmospheric Electricity Homepage

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

History

Description

Variations

Outer space and near space

Polar Aurora

Earth-Ionosphere cavity

Atmospheric layers

Thunderstorms and lightning

Electrification in the air

Research and investigation

Low altitude

High altitude

Lightning

See also

Journals

Further reading

External links