Heating Earth's Surface

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					Heating Earth’s Surface

Imbalanced heating One reason that temperatures vary across the Earth is that Earth’s axis of rotation is tilted compared to the plane of Earth’s orbit. Solar radiation is unequal partly due to the changing angle of the sunlight. The greater the area covered by solar radiation, the smaller the amount of heat per unit of area.

Thermal energy redistribution The constant movement of air redistributes thermal energy around the world. Global Wind Systems Global Winds are caused by the uneven heating of Earth’s atmosphere. More solar energy at the equator causes a low air pressure belt from hot air rising while less at the

poles causes high air pressure from cold air sinking; these differences in air pressure create a worldwide movement of air. Also, the directions of Global winds are influenced by Earth’s rotation. This is called the Coriolis effect and results in fluids and objects moving in an apparent curved path rather than a straight line. The name of a wind tells the direction it is coming from. 1. Polar Easterlies – winds from the Northern & Southern Hemispheres flow from poles to 60 degrees latitude 2. Prevailing Westerlies –flow is from 30 to 60 degrees latitude 3. Trade Winds –flow toward the equator from 30 to 0 degrees latitude

Jet Streams A jet stream is a narrow band of fast, high-altitude, westerly wind. There are in the upper troposphere & lower stratosphere. They are created by temperature & pressure differences between cold polar air & middle latitude air combined with the Coriolis effect. They strongly influence weather in the middle latitudes. Types of jet streams 1. Polar Jet Streams – major jet streams that separate the polar easterlies from the prevailing westerlies 2. Subtropical Jet Streams – minor jet streams that occur where the trade winds meet the prevailing westerlies

Jet streams and weather systems Storms form along jet streams and can generate large-scale weather systems. They affect the intensity of weather systems by moving air of different temperatures from one region of Earth to another. Local Winds Local air movements are influenced by local conditions. 1. Sea Breeze – cool wind moving from water to land (water cooler than land in the day) 2. Land Breeze – flow from cooler land to warmer water (land cooler than water at night) 3. Valley Breeze – warm valley air moves up slope (day) 4. Mountain Breeze – cooler mountain air moves down slope (night)