10b Reading/Notes
Winds and Air pressure
- Air is heated it takes up more space because it expands.
- Heated air is less compacted = density decreases, which causes the hot air to rise.
- Heated air rises and releases less pressure on the below area, which creates a low pressure on the surface of the Earth (i.e. hot air balloon).
- WInd = air moving from area of high pressure and low pressure.
- Greater the difference from the high to low pressure, the faster the wind speed.
- If every area on the Earth had the same pressure, there would be no wind.
- Winds are powered by solar energy.
Sea and Land Breezes
The only difference between the diagrams are air moves from the sea to the land for the sea breeze which is during the day and from the land to the sea for the land breeze which is during the night. These diagrams show density because the cooler is more dense. Also the sea holds its temperature longer than the land. Therefore it sinks to the ground while the warmer air rises. The cooler air pushes the the warmer air up.
Jet Streams
- A fast moving current of air located in the upper part of the troposphere.
- These rivers of are form at the boundaries of air masses with different temperatures.
- Move west to east due to Earth's rotation.
- This is a horizontal movement of wind.
- It brings the Canadian cooler air to Texas during the winter.
- These winds occur year round. This is a type of global wind.
High and Low Pressure
- Air pressure is weight of air pressing against the surface of the Earth.
- Air pressure changes as the density of air changes.
- Cool air takes up less space, and since it is compacted, its density increases.
- Matter with a greater density tends to sink in fluid such as air.
- As the cool air sinks, it causes pressure on the surface of the Earth.
- Then the air only moves from the high pressure area to the low pressure area, generating wind.
- Air pressure is the weight of the air.
- In Northern Hemisphere, low pressure moves counterclockwise and high pressure moves clockwise. In the Southern Hemisphere, it is the complete opposite.
Weather Associated with High and Lows
- Air masses are very large sections of the troposphere, which is the layer closest to the Earth's surface.
- Theses large masses of high and low pressure move across the Earth;s surface and are responsible for the weather in that area.
- Isobars are lines on a weather map, that show areas with the same air pressures and help predict areas of high and low pressures and also their wind speeds.
- Cool, dense, sinking air usually brings dry clear weather in a high pressure system.
- Warm, moist, rising air brings clouds and rain in a low pressure system.
- Rain, thunderstorms, tornadoes, and hurricanes are tied in with areas of low pressure.