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Greenhouse effect in a jar

Introduction

You can make a miniature version of the greenhouse effect in a jar!

Materials

• 1 x large glass jar (with a lid)
• 2 x small thermometers
• 2 x pieces of cardboard slightly larger than the thermometers
• 2 x rubber bands

Assembly

1. Place one thermometer on a piece of cardboard (like a sausage on bread) and secure it with a rubber band. Repeat this exercise with the second thermometer. It is important the thermometer is fully covered by the cardboard so it can be protected from the sun. Place the thermometer, wrapped in cardboard, inside the jar and put the lid on.
2. Place the other thermometer outside the jar but facing down so it is also protected from direct sunlight.
3. Place jar and thermometer on sunny window-sill making sure that the thermometers are shielded from direct sunlight by the cardboard they are attached to.
4. Record the temperatures of both thermometers every 10 minutes for an hour or daily for a week. Present data on graph, table or chart.

Results

Discuss the higher temperature and reason for it, daily variations resulting from different light conditions, and how the glass jar has a similar effect to the greenhouse gases in the Earth's atmosphere.

Greenhouse gases in the atmosphere act like the glass in a greenhouse. They allow sunlight to pass through to the Earth's surface. When sunlight hits the Earth it heats the surface. As heat rises, some of it is trapped by the greenhouse gases. Without the greenhouse gases creating what is called the natural greenhouse effect, the atmosphere and climate on Earth would be too cold to sustain life.

Last updated: 18 June 2009