The Greenhouse Effect

My daughter describes the greenhouse effect to me as follows:  "Water vapor, carbon dioxide and methane surround the earth and trap the sun's heat which keeps the earth warm and keeps us alive.  Without these, the earth would be a very cold place."  She just finished up module 10 in Apologia Biology and conducted a cool no, hot experiment to help us visualize the greenhouse effect which incidentally, lined up perfectly with the weather subunit I am doing with the younger two this week.

First she took the temperature outside in the sun then she placed that thermometer inside of a gallon sized zip lock bag and left it in the sun for about fifteen minutes.  When you try this at home you will see a difference in temperature.  The plastic bag is our acting greenhouse.  Now to amplify this and show the way carbon dioxide retains heat she took it one step further by filling the bag with carbon dioxide, sealing it withthe thermometer insde and then leaving it in the sun for another fifteen minutes.  Wow!  Big rise in temperature!

Here are the steps to getting the carbon dioxide in the bag as per Apologia.  (And it is much easier than some of the web recommended methods.)  You'll need:

• empty 2 liter bottle
• vinegar - enough to fill it about a third of the way up
• 3 tsp. baking soda

Pour vinegar into your bottle about a third of the way.  Next pour 1 tsp of the baking soda into the vinegar in the bottle.  Wait until the bubbles stop fizzing and then pour the second tsp of baking soda in.  Before you pour the third tsp of baking soda into the bottle get your bag ready.  Get all of the air out of your bag by flattening it out and leave it unsealed just enough to fit over the top of the 2 liter bottle.  You'll have to do the final step very quickly so be ready!  OK, ready?  Pour the third tsp of baking soda into the bottle and very quickly get the bag over the opening of the bottle "sealing" it with your fingers to keep any air from getting in or carbon dioxide from getting out.  Hold the bag there until the fizzing stops and tadah, you have a bag full of carbon dioxide.  Now quickly get your thermometer back into the bag and seal it completely.

This week at co-op we will be discussing temperature and the effect it has on weather, the Earth and everything on it.  We'll also be putting together terrariums so we can have mini greenhouses in our homes.