Dawn chorus (electromagnetic)
Encyclopedia
The electromagnetic
dawn chorus is an unexplained phenomenon that occurs most often at sunrise
or shortly after, that (with the proper radio
equipment) resembles the sound of the bird
s' dawn chorus
. Chorus is believed to be generated by a Doppler-shifted
cyclotron interaction
between anisotropic distributions of energetic (> 40 keV) electrons and ambient background VLF noise. Dawn choruses occur more frequently during magnetic storms
.
This phenomenon also occurs during aurorae, when it is termed an auroral chorus
.
Electromagnetism
Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...
dawn chorus is an unexplained phenomenon that occurs most often at sunrise
Sunrise
Sunrise is the instant at which the upper edge of the Sun appears above the horizon in the east. Sunrise should not be confused with dawn, which is the point at which the sky begins to lighten, some time before the sun itself appears, ending twilight...
or shortly after, that (with the proper radio
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
equipment) resembles the sound of the bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s' dawn chorus
Dawn chorus (birds)
The dawn chorus occurs when songbirds sing at the start of a new day. In temperate countries, this is most noticeable in spring, when the birds are either defending a breeding territory or trying to attract a mate. In a given location, it is common for different species to do their dawn singing at...
. Chorus is believed to be generated by a Doppler-shifted
Doppler effect
The Doppler effect , named after Austrian physicist Christian Doppler who proposed it in 1842 in Prague, is the change in frequency of a wave for an observer moving relative to the source of the wave. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from...
cyclotron interaction
Electron cyclotron resonance
Electron cyclotron resonance is a phenomenon observed both in plasma physics and condensed matter physics. An electron in a static and uniform magnetic field will move in a circle due to the Lorentz force...
between anisotropic distributions of energetic (> 40 keV) electrons and ambient background VLF noise. Dawn choruses occur more frequently 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...
.
This phenomenon also occurs during aurorae, when it is termed an auroral chorus
Auroral chorus
An auroral chorus is a series of chirps, whistles, and quasi-musical sounds in predominantly rising tones created by geomagnetic storms also responsible for the auroras. The sounds last approximately 0.1-1.0 seconds...
.