The global atmospheric electrical circuit is the continuous movement of atmospheric electricity between the

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 ...

and the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. Through the balance of thunderstorms and fair weather, the atmosphere is subject to a continual and substantial

electrical current Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by ...

. Principally,

thunderstorm A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are someti ...

s throughout the world carry ''negative'' charges to the earth, which is then discharged gradually through the air in fair weather. This atmospheric circuit is central to the study of atmospheric physics and

meteorology Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not ...

. It is used in the understanding of atmospheric electricity across the planet. In the past it has been suggested as a source of

available energy In thermodynamics, the exergy of a system is the maximum useful work possible during a process that brings the system into equilibrium with a heat reservoir, reaching maximum entropy. When the surroundings are the reservoir, exergy is the poten ...

, or communications platform. The global electrical circuit is also relevant to the study of

human health Health, according to the World Health Organization, is "a state of complete physical, mental and social well-being and not merely the absence of disease and infirmity".World Health Organization. (2006)''Constitution of the World Health Organiza ...

and

air pollution Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different types ...

, due to the interaction of negative ions and

aerosol An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be natural or Human impact on the environment, anthropogenic. Examples of natural aerosols are fog o ...

s. The effect of

global warming In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...

, and temperature-sensitivity of the Earth's electrical circuit is unknown.

History

The history of the global atmospheric electrical circuit is intertwined with the history of atmospheric electricity. For example, in the 18th century, scientists began understanding the link between

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

and electricity. In addition to the iconic

kite experiment The kite experiment is a scientific experiment in which a kite with a pointed, conductive wire attached to its apex is flown near thunder clouds to collect electricity from the air and conduct it down the wet kite string to the ground. It was p ...

s of

Benjamin Franklin Benjamin Franklin ( April 17, 1790) was an American polymath who was active as a writer, scientist, inventor, statesman, diplomat, printer, publisher, and political philosopher. Encyclopædia Britannica, Wood, 2021 Among the leading inte ...

and Thomas-François Dalibard, some early studies of charge in a "cloudless atmosphere" (i.e. fair weather) were carried out by Giambatista Beccaria,

John Canton John Canton FRS (31 July 1718 – 22 March 1772) was a British physicist. He was born in Middle Street Stroud, Gloucestershire, to a weaver, John Canton (b. 1687) and Esther (née Davis). As a schoolboy, he became the first person to determi ...

Louis-Guillaume Le Monnier Louis-Guillaume Le Monnier (sometimes written as Lemonnier) (27 June 1717 – 7 September 1799) was a French natural scientist and contributor to the Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers''. He was born ...

and John Read. Fair weather measurements from the late 18th century onwards often found consistent diurnal variations. During the 19th century, several long series of observations were made. Measurements near cities were (and still are) heavily influenced by smoke pollution. In the early 20th century, balloon ascents provided information about the

electric field An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field fo ...

well above the surface. Important work was done by the research vessel '' Carnegie'', which produced standardised measurements around the world's oceans (where the air is relatively clean).

C. T. R. Wilson Charles Thomson Rees Wilson, (14 February 1869 – 15 November 1959) was a Scottish physicist and meteorologist who won the Nobel Prize in Physics for his invention of the cloud chamber. Education and early life Wilson was born in the parish ...

was the first to present the concept of a global circuit in 1920.

Mechanism

Lightning

Lightning Lightning is a naturally occurring electrostatic discharge during which two electric charge, electrically charged regions, both in the atmosphere or with one on the land, ground, temporarily neutralize themselves, causing the instantaneous ...

strikes the earth 40,000 times per day,Electricity in the Atmosphere – Feynman Lectures
/ref> and can be thought to charge the earth like a battery. Thunderstorms generate an electrical potential difference between the earth's surface and the ionosphere, mainly by means of lightning returning current to ground. Because of this, the ionosphere is positively charged relative to the earth. Consequently, there is always a small current of approximately 2pA per square metre transporting charged particles in the form of atmospheric ions between the ionosphere and the surface.

Fair weather

This current is carried by

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

s present in the

atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...

(generated mainly by

cosmic ray Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...

s in the free troposphere and above, and by radioactivity in the lowest 1km or so). The ions make the air weakly conductive; different locations, and meteorological conditions have different

electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allow ...

. Fair weather describes the atmosphere away from thunderstorms where this weak electrical current between the

and the earth flows.

Measurement

The

voltage Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...

s involved in the Earth's circuit are significant. At

sea level Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised g ...

, the typical potential

gradient In vector calculus, the gradient of a scalar-valued differentiable function of several variables is the vector field (or vector-valued function) \nabla f whose value at a point p is the "direction and rate of fastest increase". If the gradi ...

in fair weather is 120 V/m. Nonetheless, since the conductivity of air is limited, the associated currents are also limited. A typical value is 1800 A over the entire planet. When it is not rainy or stormy, the amount of electricity within the atmosphere is typically between 1000 and 1800 amps. In fair weather, there are about 3.5 microamps per square kilometer (9 microamps per square mile). This can produce a 200+ volt difference between the head and feet of a regular person.

Carnegie curve

The Earth's electrical current varies according to a daily pattern called the Carnegie curve, caused by the regular daily variations in atmospheric electrification associated with the earth's stormy regions. The pattern also shows seasonal variation, linked to the earth's solstices and equinoxes. It was named after the Carnegie Institution for Science.

External sources

Publications

* Le Monnier, L.-G.: "Observations sur l'Electricité de l'Air",
Histoire de l'Académie royale des sciences (1752)
', pp. 233ff. 1752. * Sven Israelsson, On the Conception ''Fair Weather Condition'' in Atmospheric Electricity. 1977. * Ogawa, T., "Fair-weather electricity". J. Geophys. Res., 90, 5951–5960, 1985. * Wåhlin, L., "Elements of fair weather electricity". J. Geophys. Res., 99, 10767-10772, 1994 * RB Bent, WCA Hutchinson, ''Electric space charge measurements and the electrode effect within the height of a 21 m mast''. J. Atmos. Terr. Phys, 196. * Bespalov P.A., Chugunov Yu. V. and Davydenko S.S., ''Planetary electric generator under fair-weather condition with altitude-dependent atmospheric conductivity'', Journal of Atmospheric and Terrestrial Physics, v.58, #5,pp. 605–611,1996 * DG Yerg, KR Johnson, ''Short-period fluctuations in the fair weather electric field''. J. Geophys. Res., 1974. * T Ogawa, ''Diurnal variation in atmospheric electricity''. J. Geomag. Geoelect, 1960. * R Reiter, ''Relationships Between Atmospheric Electric Phenomena and Simultaneous Meteorological Conditions''. 1960 * J. Law, ''The ionisation of the atmosphere near the ground in fair weather''. Quarterly Journal of the Royal Meteorological Society, 1963 * T. Marshall, W.D. Rust, M. Stolzenburg, W. Roeder, P. Krehbim ''A study of enhanced fair-weather electric fields occurring soon after sunrise''. * R Markson,

'. ''Nature'', 1981 * Clark, John Fulmer, ''The Fair Weather Atmospheric Electric Potential and its Gradient''. * P. A. Bespalov, Yu. V. Chugunov and S. S. Davydenko, ''Planetary electric generator under fair-weather conditions with altitude-dependent atmospheric conductivity''. * AM Selva, et al., ''A New Mechanism for the Maintenance of Fair Weather Electric Field and Cloud Electrification''. * M. J. Rycroft, S. Israelssonb and C. Pricec, ''The global atmospheric electric circuit, solar activity and climate change''. * A. Mary Selvam, A. S. Ramachandra Murty, G. K. Manohar, S. S. Kandalgaonkar, Bh. V.Ramana Murty,
A New Mechanism for the Maintenance of Fair Weather Electric Field and Cloud Electrification
'. arXiv:physics/9910006 * Ogawa, Toshio, ''Fair-Weather electricity''. Journal of Geophysical Research, Volume 90, Issue D4, pp. 5951–5960. * ''An auroral effect on the fair weather electric field''. ''Nature'' 278, 239–241 (15 March 1979); * Bespalov, P. A.; Chugunov, Yu. V., ''Plasmasphere rotation and origin of atmospheric electricity''. Physics – Doklady, Volume 39, Issue 8, August 1994, pp. 553–555 * Bespalov, P. A.; Chugunov, Yu. V.; Davydenko, S. S. ''Planetary electric generator under fair-weather conditions with altitude-dependent atmospheric conductivity''. Journal of Atmospheric and Terrestrial Physics. * A.J. Bennett, R.G. Harrison,
A simple atmospheric electrical instrument for educational use
'

References

External links

*{{Commons category-inline Atmospheric electricity