In the next lesson, we'll wrap things up with a look at weather satellites, ice cores, the troublesome El Niýo and his little sister, La Niýa.

Assignment 7: Why Weather Matters

You can see how the thermal expansion of water works in your own kitchen. Take a large saucepan and fill it about two inches deep with water. Note the water level along the pan’s walls. Next, cover the pan and turn up the heat. (Covering the pan will help minimize the loss of water to evaporation.) When you hear it start to boil, remove the lid and look inside. (Be careful not to burn yourself.) The water level should be noticeably higher. Adding extra heat is basically giving the water molecules some extra energy to push and shove for “elbow room.” As a result, the same amount of water occupies a greater volume. Reading Assignment Global warming is a contentious issue in political circles. There’s a lot of literature out there on the subject. Please read Chapter 18 of Weather: How it Works and Why it Matters, and feel free to bring your own questions and opinions to the class forum. Extra credit: You can read more about global warming and climate change by taking a literary field trip to Antarctica in Tying Down the Wind, Chapter 20, beginning on page 229.