a. Describe global patterns of atmospheric heating and circulation
The global circulation of air is responsible for driving some of the ocean currents of the earth and assists in redistributing the solar energy reaching the earth. Thus, it moderates and impacts environments for all earth’s life. Without such redistribution and circulation, the Polar Regions would be colder and the equatorial regions hotter. According to Largen (2003), atmospheric heating and circulation is a result of the interaction of solar energy with the rotating sphere which is planet earth. When solar energy heats a sphere, differential heating occurs. The Coriolis Effect also drives atmospheric circulation and occurs when the planet’s rotational speed varies with latitude. According to Ritter (2009), global patterns of atmospheric circulation include global winds, Coriolis Effect, patterns of calm areas, and wind belts.
b. What mechanisms produce high precipitation in the tropics?
High precipitation in the tropics is as a result of condensation of atmospheric water. The tropics are usually hot and are characterized by water bodies. As such, solar radiation causes water to evaporate, and as air heats, it rises and cools with water condensing to form precipitation.
c. What mechanisms produce high precipitation at temperate latitudes?
High precipitation at temperate latitudes is as a result of seasonal changes in earth’s heating and its impact on the movement of global air masses and pressure systems. The migration of the inter-tropical convergence zone creates a drying effect in the subtropics (Furman & Guertin, 2009). However, once this shifting is into the mid-latitudes, most seasons remain humid and moist as a result of frontal activity. Thus, it is the location of the cold and hot air mass regions which are dependent on the earth’s rotation and the atmospheric circulation created by westerlies and trade winds that cause high precipitation in the temperate latitudes.
d. What mechanisms produce low precipitation in the tropics?
Low precipitation in the tropics results from the presence of mountains and hills. When there is a prevailing wind direction for moist air, the windward side of the mountain receives high precipitation (Richerson, 2004). However, the leeward side experiences little or no precipitation. This is because as the moist air goes up the windward slope, it cools and condenses to form rainfall, while only dry air blows down the leeward side.
2. Use what you know about atmospheric circulation and seasonal changes in the sun's orientation to earth to explain the highly seasonal rainfall in the tropical dry forest and tropical savanna biomes
Tropical dry forests and tropical savanna biomes lie south and north of the equatorial rain forest belt. Seasonal changes in the sun’s orientation and atmospheric circulation can explain the highly seasonal rainfall in these areas. Tropical ecosystems experience higher temperatures since more sunlight per unit area falls on tropical latitudes. Solar radiation is most intense when the sun is directly overhead, and this occurs only in the tropics. Therefore, these high temperatures encourage evaporation, and create warm and moist air. The area between the tropics is known as the inter-tropical convergence zone and is a low atmospheric pressure area (Furman & Guertin, 2009). It forms where the Southeast trade winds meet the Northeast trade winds. In this zone, low pressure and convection provide lift for the moist air. As the winds converge, they force most air upwards hence forming a portion of the Hadley cell. The air rises and cools causing water vapor to condense, and this causes heavy precipitation in the tropical forests and tropical savanna. Tropical dry forests and tropical savannas are located between the equatorial rain forests and the desert. Since warm air rises near the equator and descends at the tropics, the tropical savanna acts as the transition between the rain forests and the desert and thus receives heavy but seasonal rainfall.
Furman, T. & Guertin, L. (2009) Precipitation and the Inter Tropical Convergence Zone. Retrieved from https://courseware.e- education.psu.edu/courses/earth105new/content/lesson07/03.html
Largen, D. (2003) Atmosphere and Oceans-Circulation. Retrieved from http://mason.gmu.edu/~klargen/110lectphysenvironatmosandoceancircfall03.htm
Richerson, P.J. (2004) The Global Ecosystem. Retrieved from www.des.ucdavis.edu/faculty/Richerson/ESP30/Lecture%252014.pdf
Ritter, M. (2009, January 10) Global Patterns of Precipitation. Retrieved from http://www4.uwsp.edu/geo/faculty/ritter/geog101/textbook/atmospheric_moisture/global _patterns_of_precipitation.html