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What causes the weather?


What is the difference between weather and climate? It's easy to get climate and weather confused, but on some days they can be very different. The climate is what you expect, but the weather is what you get! You buy your clothes based on the climate, but you decide what to wear each day based on the weather.

Weather results from predictable changes in the winds and moisture of the atmosphere. Even though perfect forecasts don't exist, we can have an idea of what the weather will be like for the next couple of days based on the weather today. Beyond a few days, the weather forecast becomes less reliable.

So what causes the weather and how are these forecasts made?

The forces behind weather have a lot to do with the forces that cause the wind to blow:
  • the pressure gradient force pushes the air from high to low pressure
  • gravity pulls air toward the earth;s surface
  • friction acts against the wind near the surface
  • the coriolis force appears to turn the wind because of the earth's rotation
  • centrifugal force can affect air flowing in tight rotation (like in tornadoes)
Next page   -> under pressure

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