Climate Change: Winners and Losers
Lesson 1: The Greenhouse Effect
Page 1 Page 2 Page 3: Electromagnetic (EM) Radiation Page 4 ReviewElectromagnetic (EM) Radiation
Our planet receives "electromagnetic radiation" from the Sun. This is a fancy way of saying that we receive energy from the Sun.
"Electromagnetic" just means that the energy involves both electrical and magnetic forces. "Radiation" means that it is in the form of a wave that travels through space. In our case, it radiates from the Sun and reaches Earth.
To discuss global warming and the greenhouse effect, we will need to discuss electromagnetic energy a bit, so to save time, I am going to write "EM" whenever I mean "electromagnetic". EM radiation travels in waves containing tiny packets of energy called photons.
Here is a drawing of the EM spectrum. It is a drawing showing different types of EM radiation. Physicists call all these forms of EM radiation "light", so we will use the term "visible light" to describe what we normally call light--the EM radiation that we can detect with our eyes:
It looks confusing, so here is what I want you to notice:
- Visible light is a form of EM radiation. So are radio waves,
microwaves and X-rays;
- All these forms of EM radiation contain photons;
- The energy of the photons in the radiation increases as you move from left
to right in this drawing;
- X-rays photons are higher in energy than Microwave photons. Radio wave photons are lower in energy than visible light photons;
- Infra-red (IR) photons have slightly less energy than visible light photons. Ultraviolet (UV) photons have slightly more.