Darbas:
must understand the many processes and stages of cumulonimbus formation. The first stage or process involves the production of showers within these clouds. Next, the vertical development, which describes the rising towers to the tropopause, will be discussed. Precipitation separates cumulonimbus clouds from other cumulus clouds. The cumulonimbus can be associated with severe weather, which includes, tornadoes, waterspouts, and funnel clouds. Brief to prolonged heavy rain, hail, sleet, and flash floods are common characteristics of cumulonimbus weather patterns. Strong winds and lightning accompany these clouds to create a very severe storm system The visual aspect of shower formation frequently shows that it appears that showers fall only from clouds whose top extends to a particular height level. The generated rains are functions of height above the base and depend on certain properties such as condensed water concentration and updraft speed. The cloud depth requiredThe maritime air only requires heights of less than 2 km. This takes places so that the tops are below the 0 C level. Inland, where the surface is warmer, the required depths increase to allow for below freezing temperatures needed in the cloud tops. The first visible signs of shower development in large cumulus can often be detected by observing the dissolution of the cloud towers. Radar observations of shower formations provide valuable information. It shows cloud location, evolution of size distributions and phase of the cloud particles.
The appearance of the ice phase in cumulus above the 0 deg C level comprises a considerable fraction of the cloud water. This period is very important in the formation of a shower. A cloud whose top is above the active ice nuclei formation level of about –10 deg C can be expected to produce showers regardless of the coalescence of the cloud droplets.
Buoyancy increase in cumulus towers three ways: the freezing of liquid cloud water, release of latent heat, and precipitation of cloud water. The increase in size of a large cumulus cloud caused by convection over land rarely is steady. As the day passes, the cloud surges at a variable rate. The tallest cumulus rise between 1 to 2 km/hr and showers do not occur until near or after midday. The cloud group reaches tropopause and spread predominantly to one side producing the anvil of the cumulonimbus. Thunderstorms have been accurately measured as high as 67,000 feet and some severe thunderstorms attain an even greater height. More often the maximum height is from 40,000 to 45,000 feet. In general, air-mass thunderstorms extend to greater heights than do frontal storms. Rising and descending drafts of air are, in effect, the structural bases of
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