EQ: What effect do the Earth and the Sun have on our

weather?

ClassroomUnsquared

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/illustrations/solarsystem.html

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.gov

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

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

But the Earth does rotate onits axis. It turns from Westto East at about 1000 miles per hour at the Equator! It breaks the convection cellsinto 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

The result of unequal heating of the Earth and the Coriolis Effect create the global wind pattern shown below.

Westerlies over United StatesWesterlies over United States

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)