Noise, in analog video

Video

Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...

 and television

Television

Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...

, is a random dot pattern of static

White noise

White noise is a random signal with a flat power spectral density. In other words, the signal contains equal power within a fixed bandwidth at any center frequency...

 displayed when no transmission signal is obtained by the antenna

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...

 receiver of television set and other display devices. The random pattern superimposed on the picture, visible as a random flicker of "dots" or "snow", is the result of electronic noise

Noise (electronics)

Electronic noise is a random fluctuation in an electrical signal, a characteristic of all electronic circuits. Noise generated by electronic devices varies greatly, as it can be produced by several different effects...

 and radiated electromagnetic noise accidentally picked up by the antenna. This effect is most commonly seen with analog TV sets

Analog television

Analog television is the analog transmission that involves the broadcasting of encoded analog audio and analog video signal: one in which the message conveyed by the broadcast signal is a function of deliberate variations in the amplitude and/or frequency of the signal...

 or blank VHS

VHS

The Video Home System is a consumer-level analog recording videocassette standard developed by Victor Company of Japan ....

 tapes.

There are many sources of electromagnetic noise which cause the characteristic display patterns of static. Atmospheric sources of noise are the most ubiquitous, and include electromagnetic signals prompted by cosmic microwave background radiation

Cosmic microwave background radiation

In cosmology, cosmic microwave background radiation is thermal radiation filling the observable universe almost uniformly....

, or more localized radio wave

Radio Wave

Radio Wave may refer to:*Radio frequency*Radio Wave 96.5, a radio station in Blackpool, UK...

 noise from nearby electronic devices.

The display device itself is also a source of noise, due in part to thermal noise

Johnson–Nyquist noise

Johnson–Nyquist noise is the electronic noise generated by the thermal agitation of the charge carriers inside an electrical conductor at equilibrium, which happens regardless of any applied voltage...

 produced by the inner electronics. Most of this noise comes from the first transistor

Transistor

A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...

 the antenna is attached to.

Due to the algorithmic functioning of a digital television

Digital television

Digital television is the transmission of audio and video by digital signals, in contrast to the analog signals used by analog TV...

 set's electronic circuitry and the inherent quantization of its screen, the "snow" seen on digital TV is less random.

UK viewers used to see "snow" on black after sign-off, instead of "bugs" on white, a purely technical artifact due to old 405-line British receivers using positive rather than the negative video modulation used in Canada, the U.S., and (currently) the UK as well.

Most modern televisions automatically change to a blue screen or turn to standby after some time if static is present.

Since one impression of the "snow" is of fast-flickering black bugs on a cool white background, in Sweden

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

, Denmark

Denmark

Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

 and Hungary

Hungary

Hungary , officially the Republic of Hungary , is a landlocked country in Central Europe. It is situated in the Carpathian Basin and is bordered by Slovakia to the north, Ukraine and Romania to the east, Serbia and Croatia to the south, Slovenia to the southwest and Austria to the west. The...

 the phenomenon is often called myrornas krig in Swedish

Swedish language

Swedish is a North Germanic language, spoken by approximately 10 million people, predominantly in Sweden and parts of Finland, especially along its coast and on the Åland islands. It is largely mutually intelligible with Norwegian and Danish...

, myrekrig in Danish

Danish language

Danish is a North Germanic language spoken by around six million people, principally in the country of Denmark. It is also spoken by 50,000 Germans of Danish ethnicity in the northern parts of Schleswig-Holstein, Germany, where it holds the status of minority language...

 and hangyák háborúja in Hungarian

Hungarian language

Hungarian is a Uralic language, part of the Ugric group. With some 14 million speakers, it is one of the most widely spoken non-Indo-European languages in Europe....

, which translate to "war of the ants" or sometimes hangyafoci which means "ant soccer", and in Romanian, purici, which translates into "fleas".