Science question
roland_7707
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So the Earth turns to the east, so when you are looking at a weather map of the U.S. that would be to the right. So why is it that the weather/rain/storms that we get come from the west (left of the screen)? Shouldn't it come from the east, where it is turning to?
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1. We all live roughly on a similar latitude so "our" weather is actually only one strip of weather out of many strips of weather on the earth.
2. The uneven heating of the earth (and therefore the uneven heating of the air above the earth)
3. The Coriolis effect which makes wind in the northern hemisphere appear to turn right (and in the southern hemisphere appear to turn left).
So here goes my explanation to answer your question and I'll try to not be long-winded. The sun beats mercilessly on the equator making it the hottest place on earth. The hot air rises and creates a planet wide strip of low-pressure. Above and below the equator, where this wind ends up, become strips of relatively high pressure. The Arctic and Antarctic, due to several reasons, are also high pressure systems. In between these caps of high pressure and the high pressure N and S of the equator is another strip of low pressure. So, starting at the middle and working north you have the equator (low), the tropics (high), the temperates (low) and the arctic (high).
Confused yet? It gets better. At the surface of the earth wind blows from high pressure to low pressure. But it doesn't blow straight because the earth is spinning easterly. As the wind tries to blow straight the earth spins so the wind doesn't end up where it was originally pointed. Since we don't see the earth spin what WE SEE is the wind appear to turn right, the Coriolis Effect.
The wind which blows from the tropic high back towards the equatorial low (S) takes a right hand turn and becomes the NE Trade Winds. The wind which blows from the tropic high towards the temperate low (N) takes a right hand turn and becomes the Prevailing Westerlies ("our" weather). The wind which blows from the arctic high towards the temperate low (S) takes a right hand turn and becomes the Polar Easterlies. The southern hemisphere is a mirror image of this.
There are a lot of factors which make these strips of pressure fluctuate with the seasons across the globe as well as fluctuating between land and ocean coverage but in general this is the base of where our wind comes from. I hope this helped.