Global and Local Winds
Global Winds - Powered by uneven heating of Earth’s Surface
Warmest Region is at the equator - the coldest at the poles, due to uneven heating of Earth’s Surface
If Earth did not spin, there would be 2 wind belts, each moving warm air from the equator to one of the poles, and cold air from the poles down to the equator.
Warmest Region is at the equator - the coldest at the poles, due to uneven heating of Earth’s Surface
If Earth did not spin, there would be 2 wind belts, each moving warm air from the equator to one of the poles, and cold air from the poles down to the equator.
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But Earth SPINS! Coriolis Effect - the way Earth’s rotation causes the winds to curve The Coriolis Effect causes 6 winds belts to form |
Europeans used the trade winds, as well as ocean currents, to help them travel by sea.
- From Europe to the Americas - Trade Winds - deposit Europeans near Cuba
- From Americas to Europe - Westerlies carry ships towards Europe
Calm Areas - Little/No Wind
Doldrums - near 0°
Little Temp Difference = Little Wind
The air rises more or less straight up around the Equator. Straight up = no surface wind
Horse Latitudes - 30° N and S
Where the Trade Winds and Westerlies meet, there is an area with very little wind...it was also feared by sailors. According to legend, crews of stranded ships would throw horses overboard to conserve water as long as possible and increase their chances of survival.
Doldrums - near 0°
Little Temp Difference = Little Wind
The air rises more or less straight up around the Equator. Straight up = no surface wind
Horse Latitudes - 30° N and S
Where the Trade Winds and Westerlies meet, there is an area with very little wind...it was also feared by sailors. According to legend, crews of stranded ships would throw horses overboard to conserve water as long as possible and increase their chances of survival.
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The JET STREAM Strong belt of winds that travel near the top of the troposphere. Flows from WEST to EAST across North America, in a serpentine pattern. Has a MAJOR impact on weather patterns. |
Local Winds-
Local winds can be caused by uneven heating of the Earth, just like Global Winds. Different materials on the surface of the Earth heat up at different rates, leading to pressure differences and small scale winds.
Specific Heat - Amount of thermal energy required to heat a material 1°
Materials - specific heat
Water - 4200
Sand - 835
Clay - 920
Granite - 790
Dry Soil - 810
Water does not heat up as fast as other materials, but it holds on to heat longer
Other materials heat up faster and cool off faster, this can lead to breezes developing around large bodies of water, where pressure differences occur due to the temperature of the surfaces the air touches.
Land vs. Water
Type of Breeze
Sea Breeze - During the day - Wind off sea; towards land
Land Breeze - At night - Wind off land; towards Sea
Why
Sea Breeze - During the day, water reflects sunlight and heats more slowly than land. Land quickly warms air above it, this air rises and cooler air located over the sea flows in to take its place, creating a breeze.
Land Breeze - At night, the land cools more rapidly, water retains more heat and warms air above it. This means that the warmest air is now above the ocean - it rises...then relatively cooler air that was over the land flows in, creating a breeze that blows from land to sea.
Specific Heat - Amount of thermal energy required to heat a material 1°
Materials - specific heat
Water - 4200
Sand - 835
Clay - 920
Granite - 790
Dry Soil - 810
Water does not heat up as fast as other materials, but it holds on to heat longer
Other materials heat up faster and cool off faster, this can lead to breezes developing around large bodies of water, where pressure differences occur due to the temperature of the surfaces the air touches.
Land vs. Water
- Land transfers heat more readily than water - it warms and cools more quickly
- Water requires more energy before it increases its temperature and is also slower to release its energy
Type of Breeze
Sea Breeze - During the day - Wind off sea; towards land
Land Breeze - At night - Wind off land; towards Sea
Why
Sea Breeze - During the day, water reflects sunlight and heats more slowly than land. Land quickly warms air above it, this air rises and cooler air located over the sea flows in to take its place, creating a breeze.
Land Breeze - At night, the land cools more rapidly, water retains more heat and warms air above it. This means that the warmest air is now above the ocean - it rises...then relatively cooler air that was over the land flows in, creating a breeze that blows from land to sea.