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The Greenhouse Effect


What is a Greenhouse?

A greenhouse is a type of building used to grow plants. The walls of the house are made with glass or plastic so that light can easily enter it from all sides. The greenhouse then captures the heat from the sun and allows people to grow plants. Some of the heat from the sun escapes, but some of the heat is trapped which raises the temperature of the greenhouse.

The Greenhouse Effect is the term we used to describe what happens when the suns energy is trapped and warms up the air. If you look at the picture above you can see how that happens, but let's do an experiment to see for ourselves!

Thermometer Experiment

We will need two thermometers and a plastic bottle to do our test.

  1. Put one thermometer in the bottle and then place it out in the sun. The bottle will act as our 'greenhouse'.
  2. Place the other thermometer next to the one in the bottle, also in the sun.
  3. Read the temperatures of both thermometers. They should be the same!
  4. Wait for 15 minutes and then read the temperatures of both thermometers again.

You can use a chart like this to to keep track of your temperatures:

  • Temperature inside the bottle: At Start ____ After 15 min _____
  • Temperature outside the bottle: At Start ____ After 15 min _____

After 15 minutes you will find that the temperature of one thermometer is higher than the other. Which one is it? Why is it hotter than the other?

Answer:

The thermometer inside the bottle was hotter, this is because of the greenhouse effect! The plastic walls of the bottle reflect infrared radiation (heat) back into the bottle which raises the temperature.

The Greenhouse Effect and Global Warming

In our last lesson we learned that the temperature around the world has been increasing due to Global Warming. The greenhouse effect helps to explain why the temperature is rising. When sunlight passes through the atmosphere and hits the earth it creates infrared radiation (another way to say heat). Certain gases in the atmosphere catch this heat, which warms up the air temperature. If it wasn't for the Greenhouse Effect the world would be a very cold place and we probably wouldn't be able to live here! You can see the different ways sunlight moves through the atmosphere in the picture below. In our next lesson we will look closer at how the energy from the sun gets trapped due to Greenhouse Gases. While the Greenhouse Effect helps to make earth a nice place to live, we will see that due to human activity and an increase in Greenhouse Gases we are making our planet much hotter than normal.

The Gathering Storm

This week we are going to watch a video called Coastal Erosion from our series The Gathering Storm. It can be viewed by clicking HERE. Afterwords head over to the discussion page!