Atmosphere Atmospheric Circulation Is Initiated When Mass

Atmosphere

Atmospheric circulation is initiated when mass moves in the atmosphere. The motion can be vertical or horizontal. Atmospheric forces cause air to move, modifying the difference in pressure. Vertical and horizontal movements combine to modify temperature and pressure at local levels (Chou & Neelin, 2004).

High precipitation in the temperate regions is occasioned by differential solar heating of the planet due to axial tilt, rotation and proximity to the sun. The sun rays hit the equator at a direct angle between 23° 26'22"N and 23°26'22"S. Solar radiation that reaches that reaches the atmosphere is more intense between the tropic of cancer and the tropic of Capricorn. Anywhere else, the solar radiation hits the earth surface at an angle and is therefore less intense (Chou & Neelin, 2004).

The closer a place is to the poles, the smaller the angle and the less intense the radiation. Trade winds north of the equator blow from the north east and south east to the south of the equator. When the trade winds of the two hemispheres meet at the equator, the air rises. When the rising air cools, clouds and rain develop. The cycling rise and fall is called the Hadley cell. The resulting bands of cloudy and rainy weather near the equator create temperate zones (Chou & Neelin, 2004).

Because the tropics are warmer the air holds more moisture that is never lost until it interacts with colder air. Blockage of moist-laden winds by a mountain range causes low precipitation on the lee-ward side of the mountain as the winds are forced to shed all its moisture on the wind-ward side of the mountain as rain.

Mechanisms producing high precipitations at the tropics include rain, snow and sleet. High precipitation occurs when the atmosphere becomes full of water vapor which condenses and then precipitates. The trade winds of the two hemispheres make the air to rise. As the rising air cools, cloud and rain develop.

The highly seasonal rainfall in the tropical dry forests and the tropical savanna biomes are attributed to atmospheric circulation and seasonal changes in the sauna's orientation. In fact, it is the global circulation patterns that create the predictable regional climate zones. At the equator's low pressure belts and at 50 to 60 degree north and south latitudes there are abundant precipitations. At latitudes around 30 degree north and south, dry air descend from the high pressure belt similar to that which happens in a see breeze circulation. This dry air that descends from the high pressure belt produces arid zones that include Earth's major deserts. Because Coriolis Effect prevents mass and heat from moving readily to polar latitudes, temperatures decline and pressures increase sharply between middle latitudes and the Polar Regions (Chou & Neelin, 2004).