Electricity in Nature: Plasma

What is it?

Plasma is a word that can be used to define the liquid in which your blood cells are suspended, the “whey” in curds and whey, a green variety of quartz, or, for our purposes, a highly ionized gas that contains an (approximately) equal number of protons and electrons. Plasma is commonly considered the fourth state of matter, apart from solids, liquids, and gases.

All of the stars in the universe are made of plasma, and lightning, St. Elmo’s Fire, and polar aurorae are all considered “terrestrial plasma”. What we see as “lightning bolts” are actually “striations” (strings, or filaments) of plasma.

Plasma is considered the most common form of matter, which at first seems strange since most of it is not visible, but it comprises about 99% of the universe.

How Does It Relate to Electricity?

To understand what plasma has to do with electricity, we’ve got to understand it’s place in the atmosphere. Did you know that there is an entire portion of the earth’s atmosphere that is made up of plasma?

The earth’s atmosphere is divided into four main sections: the troposphere, stratosphere, mesosphere, and the thermosphere. The thermosphere gradually dissipates into the exosphere, also known as “outer space”.

Within the thermosphere, solar radiation causes the air to become ionized (creating the ionosphere). For a little reference, check out this awesome infographic! Ionized air is made up of molecules that have become charged by adding or removing charged particles (electrons or ions). When solar radiation collides with the molecules in the thermosphere, it dislodges the charge particles, which can then float freely for a short time (as free electrons) because of the vast space between molecules at this height, before attaching to a new molecule. When the air is in this state of ionization, it is considered a plasma. Plasma, while similar to gas, is different in that it is a much better conductor of electricity (due to the high volume of charged particles), and it responds to electrical and magnetic fields much more strongly than gases. Electricity is very basically defined as the movement of electrons form one molecule to another, so plasma is suspended in an “in between” state that conducts electricity very, very well.

The ionosphere absorbs the most “energetic” rays from the sun, and reflects radio waves back to earth. When the sun is particularly active, ionization in the thermosphere increases, and the result is aurora borealis and aurora australis.

Check out different types of plasma!

Practical Applications

The practical application of plasma can be seen in neon and fluorescent lighting, arc welding tools, and plasma-screen TVs. The most promising application has yet to come to fruition, however, in the form of fusion.