How can plants be grown during cold seasons? Inside a greenhouse it stays nice and warm even if there are snowmen outside. Learn how Earth is like a giant greenhouse in this lesson.

How Does a Greenhouse Work?

Have you ever left something like a candy bar or a banana in a closed car on a summer day? When you find it, it has usually melted into a soggy mess! What caused it to get so hot in the car? The answer can be found in something called the greenhouse effect, and it works not just inside hot cars, but on the whole Earth.

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A Greenhouse
Greenhouse

Our atmosphere, Earth’s protective layer, is made up of different kinds of gasses. Some of these gasses act like a greenhouse. Just like the windows in a car allow the sunlight in but do not allow the heat to get out, a greenhouse works the same way. The clear material of a greenhouse allows the sunlight in so the plants can grow, but the heat that is generated is not able to leave, keeping the plants warm when it may be too cold for them to grow outside.

Most life on Earth can thank this effect, also called the greenhouse effect, for keeping us nice and warm. Without the greenhouse gasses that keep heat trapped inside our atmosphere, most of the heat from the sun would escape right back out into space. This would only be good if you were a snowman.

What are the Greenhouse Gasses?

Can you see air? It’s hard to imagine that air is actually something that has mass and takes up space. But air is actually matter. If you weighed an empty balloon and a balloon full of air, it would show you that air has mass. So what is air made of? Most of our atmosphere (78%) is nitrogen. Nitrogen is not a greenhouse gas. Oxygen makes up the next biggest part (21%). Oxygen is not a greenhouse gas. That means only a very small percent of gasses create the greenhouse effect.

Greenhouse Earth
Earth as a Greenhouse

Some of the gasses that contribute the most to Earth’s warmth are water, carbon dioxide and methane. These particular gasses allow the sunlight to pass through, warming the Earth, but they keep that heat from escaping right back into space. What do you do when you are cold at night? You put on a blanket, right? Greenhouse gasses are like a blanket for the whole Earth.

Life with Snowmen

What would it be like without the greenhouse gasses? About a third of the sun’s energy is reflected by our outer atmosphere and never reaches the Earth. Most of the energy that reaches the earth is then reflected back up as heat. Without the greenhouse gasses acting like a blanket, the world would be 15 to 30 degrees colder. That might not sound like much, but for the whole world it’s a lot. That would mean lots of snowmen!

Snowman
Snowman!

Can there be too much of a good thing? In the case of greenhouse gasses, yes. Some scientists believe humans are creating too many greenhouse gasses through all our activities like energy production, automobile use, factories and agriculture. If we add too many greenhouse gasses to the atmosphere, that’s a mighty hot blanket that we can’t kick off. No more snowmen! That theory is known as Global Warming.

Lesson Summary

The greenhouse effect is named after the principle of a greenhouse. One percent of the gasses in our atmosphere, like carbon dioxide and methane, create a similar effect as a greenhouse. Sunlight is transferred in through the gas matter, but heat is trapped like a giant blanket. Without the greenhouse effect, Earth would be a lot colder. Too many greenhouse gasses could cause Earth to be too warm and contribute to Global Warming.