The Greenhouse Effect

What is the greenhouse effect?

Have you ever been inside a greenhouse? Greenhouses are very warm inside all year round — this is how plants are grown inside them, even in the winter. The way a greenhouse works is that the glass they are built from allows the sun's rays to shine in, but then prevents the heat from escaping once it is inside.

Now, think of the Earth as being a giant greenhouse. The gases on Earth act just like the glass; this is how the Earth gets warm from the sun even though it is about 93 million miles away. The gases allow the sun's rays to shine in, but then prevent the heat from escaping the Earth. This way of warming the Earth's surface is referred to as the greenhouse effect.

Greenhouse Effect

Here are the main gases in the Earth's atmosphere that cause the greenhouse effect:

Water vapour
Carbon dioxide
Methane
Nitrous oxide

Although the Earth's atmosphere naturally contains these greenhouse gases, over the past few decades their presence has increased, causing the temperature of the earth to increase. The following human activities are the biggest contributors to the increase of greenhouse gases:

burning gasoline to drive cars and trucks
burning oil, coal or wood to produce electricity for heating, cooling and other purposes
burning forests to clear land

Try this easy experiment: Take two jars and put a teaspoon of water in each jar. Put a lid on just one jar. Place both jars in a sunny spot. After a few hours, check on the jars. You'll see that the open jar hasn't changed, but the closed jar will be steamy and hot inside. What happened? The heat from the sun could not escape from the closed jar, just like it can not escape from the Earth's surface.