27 January 2009
Weather Systems - Precipitation In The Making
By: Vince Paxton
For those who study weather on a daily basis, movement of air masses is at the heart of most changes in weather conditions. These huge areas of warm air or cold air (weather fronts) move up or down in the atmosphere, as well as horizontally, sometimes covering hundreds of miles in a short time. The sun does not heat the atmosphere on a consistent basis. Variations in temperature occur, depending on the location. The large masses of air move about, part of nature’s attempt to maintain balance.
But it is not just the movement of a single air mass that is key in determining the type of weather we experience. Instead, the confrontation between two masses of air often cause significant changes in conditions. A mass of air moving into a particular region will encounter another mass. The area where these two air masses meet, where the conflict occurs, is commonly called a front.
For general weather watching purposes, when a cold air mass moves in and attempts to replace a warmer mass, meteorologists and weather watchers call it a cold front. When the moving air mass is warm and it meets a cold air mass, the area of contact is called a warm front.
However, movement of these huge areas of air is not limited to straight-line, horizontal activity. A warm mass encountering a colder section of air will ride over the top of the cooler mass, causing clouds to be formed through condensation. Essentially, the difference in temperature between the two air masses triggers a reaction in the water vapor of the masses. Most of the time, an observer of this activity will see cirrus clouds high in the atmosphere, with clouds forming at a slightly lower level later. Heavy stratus clouds appear, generally producing precipitation and windy conditions.
Over long periods of time, there is some consistent frontal activity, which produces the various climate conditions found around the world. Scientists have learned that weather changes produced by a cold front will often be more volatile than the activity caused by a warmer mass of air. A cold front meeting a warm air mass forces the warmer up, quickly. This movement results in unstable conditions and convection. Massive cumulus clouds will result, with storms forming along the boundary between the two masses of air. In addition, the rising air produces a low-pressure area, with stronger winds resulting. Most of the time area residents will experience heavy rain. Precipitation tends to linger after the passage of this frontal activity.
Less common but still of interest is the overtaking of a slow-moving warm front by a cold air mass. The warm air is pushed to a higher elevation but the air masses continue to travel together. This front between two air masses, one above another, is known as an occluded front, which usually have stratus clouds and some rain as companions.
While displacement of one air mass by another is quite common, sometimes these two sections of the atmosphere have the same strength. When one cannot replace the other, meteorologists and weather watchers see a stationary front. Extended periods of cloudiness and precipitation are the features of this unique climate condition.
Article Source: http://www.articlesnatch.com
About the Author:
Vince Paxton published essentially for http://www.alicante-spain.com , a web publication on the topic of weather fronts and climate. His writings on weather forecast for benidorm spain are found on his site .