Hiss electromagnetic palmer 2003-01-30 T215005

Electromagnetic In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after the strong force, and it is the dominant force in the interactions of a ...

hiss is a naturally occurring

Extremely Low Frequency Extremely low frequency (ELF) is the ITU designation for electromagnetic radiation (radio waves) with frequencies from 3 to 30 Hz, and corresponding wavelengths of 100,000 to 10,000 kilometers, respectively. In atmospheric scien ...

Very Low Frequency Very low frequency or VLF is the ITU designation for radio frequencies (RF) in the range of 3–30 kHz, corresponding to wavelengths from 100 to 10 km, respectively. The band is also known as the myriameter band or myriameter wave as ...

electromagnetic wave In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, which propagate through space and carry momentum and electromagnetic radiant energy. It includes radio waves, microwaves, infrared, (visible) ligh ...

(i.e., 300 Hz – 10 kHz) that is generated in the plasma of either the Earth's

ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an im ...

magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior dyna ...

. Its name is derived from its incoherent, structureless spectral properties which, when played through an audio system, sound like

white noise In signal processing, white noise is a random signal having equal intensity at different frequencies, giving it a constant power spectral density. The term is used, with this or similar meanings, in many scientific and technical disciplines, i ...

(hence the

onomatopoetic Onomatopoeia is the process of creating a word that phonetically imitates, resembles, or suggests the sound that it describes. Such a word itself is also called an onomatopoeia. Common onomatopoeias include animal noises such as ''oink'', '' ...

name, "hiss").

Varieties

Hiss may be observed in any of several varieties depending on local time and

L-shell The L-shell, L-value, or McIlwain L-parameter (after Carl E. McIlwain) is a parameter describing a particular set of planetary magnetic field lines. Colloquially, L-value often describes the set of magnetic field lines which cross the Earth' ...

of the observer: * ''Plasmaspheric hiss'' is generally observed within the

plasmasphere The plasmasphere, or inner magnetosphere, is a region of the Earth's magnetosphere consisting of low-energy (cool) plasma. It is located above the ionosphere. The outer boundary of the plasmasphere is known as the plasmapause, which is defined b ...

, peaking in frequency slightly below ~1 kHz and rarely exceeding 3 kHz. * ''Exo-hiss'' and ''ELF hiss'' are two varieties of hiss observed outside of the

, both having a spectrum similar to that of plasmaspheric hiss. * ''Midlatitude hiss'' is generally observed outside of the plasmasphere and tends to have frequencies between 2 and 10 kHz. * ''Auroral hiss'' is observed in the auroral zones of the Earth and can extend up to several hundred kHz.

Generation mechanisms

There are several proposed generation mechanisms for plasmaspheric hiss in particular, including: * Generation from discrete chorus emissions * Generation via electromagnetic impulses from terrestrial

lightning Lightning is a naturally occurring electrostatic discharge during which two electrically charged regions, both in the atmosphere or with one on the ground, temporarily neutralize themselves, causing the instantaneous release of an average ...

, specifically via lightning-generated

whistlers Whistler may refer to: * Someone who whistles Places Canada * Whistler, British Columbia, a resort town ** Whistler railway station ** Whistler Secondary School * Whistler Blackcomb, a ski resort in British Columbia * Whistler Mountain, Brit ...

* Generation through coherent nonlinear interaction with energetic electrons near the equatorial plasmasphere

References

{{DEFAULTSORT:Hiss (Electromagnetic) Electrical phenomena Geomagnetism

Varieties

Generation mechanisms

See also

References