1. EQ: What effect do the Earth and the Sun have on our weather? Classroom Unsquared

2. The Sun is a star at the center of our solar system. It is mostly made of hydrogen and helium gas. It is a nuclear energy furnace giving off light and heat. 1,300,000 Earths would fit inside the Sun. The Sun is 150,000,000 kilometers from the Earth, or 11,600 Earths lined up side- by-side. http://chandra.harvard.edu/resources/illustr ations/solarsystem.html

3. Solar Energy Reaching the Earth This diagram shows what happens to the sun’s light and heat when it reaches Earth. Notice that about 50% of the energy is absorbed by the Earth’s surface, thus heating land and oceans. earthobservatory.nasa.go v

4. Heating of Earth’s surface is greatest at the Equator and less toward the Poles. The surface heats the atmosphere. http://en.wikibooks.org/wiki/High_School_Earth_Science/Climate_and_Its_Causes

5. Let’s see what happens to the unequal heating of the Earth’s atmosphere. Let’s pretend that the Earth did not rotate on its axis. Heated air at the Equator would tend to rise because it is less dense. Cold air at the Poles is heavier and it sinks. Pixabay.com HOT COLD The sinking cold air flows south to replace the rising hot air, and a convection cell is formed. The moving air is wind. The surface winds in the northern hemisphere would be from the north and the opposite to the south. Equator North Pole South Pole

6. But the Earth does rotate on its axis. It turns from West to East at about 1000 miles per hour at the Equator! It breaks the convection cells into smaller ones and makes the winds appears to curve to the right in the northern hemisphere and to the left in the south. This motion is called the Coriolis Effect. See how it works to the right. A marble is placed at the center of a rotating disk and released. http://commons.wikimedia.org/wiki/File %3ACorioliskraftanimation.gif Actual Path Apparent path on the disk http://en.wikipedia.org/wiki/Earth's_rotation

7. The result of unequal heating of the Earth and the Coriolis Effect create the global wind pattern shown below. Westerlies over United States

8. Air that stays over one area for a long time takes on the temperature and moisture content of that area. The air is now called an air mass. In the summer, warm air masses can grow and move north. In the winter, cold air masse can grow and move south. http://en.wikipedia.org/wiki/Air_mass Symbols: A = Arctic (very cold) P = Polar (cold) T = Tropical (warm) c = Continental (dry) M = Maritime (humid)