Wx Savvy | Climate

What Is The Greenhouse Effect?

(Not that kind of green house) (This kind of greenhouse)

Did you know, we wouldn't be able to live on this planet unless the greenhouse effect worked?

The greenhouse effect is the name for the process where our atmosphere absorbs heat energy thereby warming the planet to a comfortable level. By comfortable, I mean our global temperatures allow us to live and grow food and basically sustain life. Let's dive into the details...

Our planet actually warms from the bottom up. Huh?

That means that the warmest air is near the surface and it's colder higher up, like on Mount Everest. This is easily seen by the snow covered peaks of the mountains, while you experience a nice warm day standing at the mountain base. So now that you believe me, you can ask why?

Because the sun's form of radiation (short-wave) isn't easily absorbed by our atmosphere's particles. Our atmosphere contains nitrogen, oxygen, carbon-dioxide, water (mostly in vapor form), methane and a bunch of other stuff not worth mentioning here. So these atmospheric particles are kind of snobby. They don't want to absorb the sun's short-wave radiation. Noooooo, they are too good for short-wave radiation, they want the good stuff...long-wave radiation.

So, the sun's energy in the form of sunlight goes through our atmosphere without being absorbed. Then the sunlight energy hits the earth and is absorbed by the land and oceans. The land and oceans then emit energy back into the atmosphere in the form of long-wave radiation. Now you have radiation being emitted from the earth upwards, and it is in the long-wave radiation form, thus being absorbed by our snobby atmospheric particles. Thus, the atmosphere heats from the surface upwards, or bottom up.

A greenhouse acts in a similar way to our atmosphere, but not exactly. The reason the analogy is made is because the plants absorb the short-wave radiation from the sun which enter through the panes of glass in the greenhouse. Then, the plants emit their own energy back into the air as long-wave radiation. This long-wave radiation is then easily absorbed by the air particles in the greenhouse and results in a warming of the air. However, what truly keeps the air warm, is the roof and the walls. And our atmosphere has no roof and walls.

So, the "greenhouse effect" is a bad name because the glass walls prevent convection. This means it prevents mixing of the inside air with the outside air. Our atmosphere is always mixing so the term greenhouse effect doesn't relate well to the actual atmospheric processes. However, because it is universally used, it's easiest to press on using the misnomer "greenhouse effect", but now you'll know the truth.

The gasses in our atmosphere that are really good at absorbing long-wave radiation (and thus absorbing heat) are called greenhouse gasses. These greenhouse gasses make it possible to sustain life on earth because they absorb heat energy thus keeping our planet warm enough for us to live and for vegetation to grow.

But what happens if there are too many greenhouse gas particles in the air? Does the air continue to heat up until we start to cook in our own atmosphere? This question is why global warming is linked to the greenhouse effect, although it must be made clear they are not the same thing.

The debate over global warming is if humans are responsible for putting too many greenhouse gases in the air and thus humans are responsible for the warming on the planet. We won't get into that right now, but at least you have a better understanding of the greenhouse effect.