Weather Intro 2011

Weather Weather is caused by the unequal heating of the surface of the planet. This occurs in two ways.

Solar Energy and Latitude Since the Earth’s surface is a sphere, the equator receives direct sunlight while the light that reaches the poles is more spread out. So the higher you get in latitude, the lower the temperatures will be.

Unequal Heating Weather is caused by the unequal heating of the land and water. At the beach you have noticed that the sand can be very hot on your bare feet, but the water is quite cool. But sand and water receive the same amount of energy from the sun. So why don’t they both heat up equally?

Specific Heat Specific heat is the amount of energy it takes to heat 1-kg of a material by 1°C. Sand has a lower specific heat, so it heats (and cools) rapidly. Water has a very high specific heat, so it heats slowly, but also cools slowly.

Unequal Heating So the oceans will take a long time to heat up, and an equally long time to cool off. Land will heat up quickly and cool down just as fast. You really notice this at the beach. The sand cools rapidly after the sun goes down, but the water stays about the same temperature.

Temperature and Winds This difference in temperature will cause warm air to rise (low Pressure) and cool air to sink (high pressure). This difference in pressure causes wind to blow (high pressure to low pressure).

Temperature and Rain This temperature difference will also affect how much moisture the air will hold, as warm air holds more water vapor than cold air. So when the air gets colder, it can’t hold as much water so it precipitates.

Conclusion So weather is caused by this uneven heating. Soil absorbs energy differently than water. Energy is concentrated at the equator and spread out at the poles.