engineering

Global atmospheric electrical circuit

Global atmospheric electrical circuit is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Global atmospheric electrical circuit rather than just read about it. In short: A global atmospheric electrical circuit is the continuous movement of atmospheric charge carriers, such as ions, between an upper conductive layer (often an ionosphere) and surface. The global circuit concept is closely related to atmospheric electricity, but not all atmospheres necessarily have a global electric circuit.

Key takeaways

Global atmospheric electrical circuit belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Global atmospheric electrical circuit to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Global atmospheric electrical circuit from memory before moving on to harder problems.

Reference excerpt

A global atmospheric electrical circuit is the continuous movement of atmospheric charge carriers, such as ions, between an upper conductive layer (often an ionosphere) and surface. The global circuit concept is closely related to atmospheric electricity, but not all atmospheres necessarily have a global electric circuit. The basic concept of a global circuit is that through the balance of thunderstorms and fair weather, the atmosphere is subject to a continual and substantial electrical current. Principally, thunderstorms throughout the world carry negative charges to the ground, which is then discharged gradually through the air away from the storms, in conditions that are referred to as "fair weather". This atmospheric circuit is central to the study of atmospheric physics and meteorology. The global electrical circuit is also relevant to the study of human health and air pollution, due to the interaction of ions and aerosols. The effects of climate change and temperature-sensitivity of the Earth's electrical circuit are currently 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 and electricity. In addition to the iconic kite experiments of Benjamin Franklin 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, Louis-Guillaume Le Monnier 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 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 was the first to present the concept of a global circuit in 1920.

Mechanism

Lightning

There are about 40,000 thunderstorms per day across the globe, generating roughly 100 lightning strikes per second, which 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 ground. 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 ions present in the atmosphere (generated mainly by cosmic rays in the free troposphere and above, and by radioactivity in the lowest 1 km or so). The ions make the air weakly conductive; different locations, and meteorological conditions have different electrical conductivity. Fair weather describes the atmosphere away from thunderstorms where this weak electrical current between the ionosphere and the ground flows.

Measurement The voltages involved in the Earth's circuit are significant. At sea level, the typical potential gradient 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. In fair weather, there are about 3.5 microamps per square kilometer (9 microamps per square mile).

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.

See also Atmospheric electricity Geophysics Earth's magnetic field Upper-atmospheric lightning Space charge Telluric currents

External sources

Publications

References

External links Media related to Global atmospheric electrical circuit at Wikimedia Commons

Illustrations

Worked examples

Example 1 — a first encounter with Global atmospheric electrical circuit

Start with the simplest possible case. Write down what Global atmospheric electrical circuit claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Global atmospheric electrical circuit before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Global atmospheric electrical circuit ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Global atmospheric electrical circuit

In research: Global atmospheric electrical circuit appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Global atmospheric electrical circuit in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Global atmospheric electrical circuit is common in secondary-school and first-year university syllabi. It links to neighbouring topics Atmospheric electricity, so understanding it makes those chapters shorter.
In everyday life: Look for Global atmospheric electrical circuit outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Global atmospheric electrical circuit” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Global atmospheric electrical circuit in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Global atmospheric electrical circuit means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Global atmospheric electrical circuit out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Global atmospheric electrical circuit in simple terms?

Why does Global atmospheric electrical circuit matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Global atmospheric electrical circuit?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Global atmospheric electrical circuit.