Metereology Essay Example | Topics and Well Written Essays - 1500 words

Metereology - Essay Example When a body of air rises, it moves from higher pressure to lower pressure. In so doing it must expand, and as it does so, its temperature is reduced. One can calculate the amount of cooling to be expected when the air is lifted by a fixed amount. If the air is dry and no heat is added or taken away as the air ascends, it cools at the rate of 1.0C per 100 meters. This is known as the dry adiabatic lapse rate. Once a cloud has begun to form, the cooling effects caused by the expansion of the rising air are partially offset by the heat released during the condensation process. Evaporation causes cooling. When condensation occurs, the reverse is true; heat is added. If the rate of ascent of air, which may be called the updraft speed (Sloane and Tesche 1991), is quite high, the air may cool so fast that condensation cannot proceed fast enough to keep the air at saturation. In this case the air may become supersaturated. The equations show that once this happens the smaller droplets grow m ore rapidly than the large ones. The final condition is one with clouds having a narrow range of droplet sizes. The main processes which influences cloud formation are condensation or deposition (Brasseur et al 1999). The difference in temperature always causes a difference in atmospheric pressure, which in turn causes the wind. When the resulting winds are confined to small areas, not more than a few miles in extent, they blow directly from high pressure to low pressure, as one would expect. Weather front can be identified as a boundary between air masses of hot and cold air (Brasseur et al 1991). The main types of fronts are cold front and warm front, stationary front and occluded front. The typical wind circulation about a well-developed low or a well-developed stationary high is often useful in predicting lower-level winds. Several hundred feet above the ground, these circulatory winds blow nearly parallel to the isobars. Fronts are always described as zones of transition, the types of the front depends upon the direction and air masses (Sloane and Tesche 1991). The cold front, extending southward and southwestward from the low center, is also a wedge of cold air underlying warm air -but an a ctive, undercutting wedge, a steeper wedge than the warm front, a wedge that is steadily advancing eastward and southeastward in such a way as to crowd out the warm air more or less violently and to thrust it aloft. The warm front extends east and southeast from the low center, with the warm sector advancing behind it from the southwest and the colder air retreating slowly ahead of it towards the north (Sloane and Tesche 1991). Occlusion is the combination of warm and cold fronts where the latter has overtaken the former. The occlusion itself usually extends gradually southward as more and more of the warm sector is forced above the surface by the closing wedges of colder air. Stationary front is defined as a front which does not move (Sloane and Tesche 1991). Weather Systems: hurricanes, tornadoes, thunderstorms The term hurricane is usually used to describe tropical storms and cyclones. Also, hurricane can be defined as the strongest level of wind according to the Beaufort scale. Unstable air above these steaming areas of warm and azure sea is continually building up