Cold front, Warm front, Stationary front.
2007-10-24 13:56:44
·
answer #1
·
answered by Anonymous
·
0⤊
0⤋
When contrasting air masses lie side by side,the narrow zone of discontinuity,separating the two air masses is called a front.
If the colder air mass actively displaces the warmer air at the surface,then the front is refered to as a cold front.
If the warmer air flows actively upwards over the cold air mass below, then it is called a warm front.
When the two air masses lie side by side without trying to replace each other, the front is refered to as quasi-stationary(or simply stationary) one.The polar front is an example for this.
Cold front moves faster than the warm front and if it advances towards the warm front,it overtakes the warm front first near the centre and gradually outwards.The warm air between them is displaced upward and forward.This displacement of the air in the warm sector is an important step in the development of the extra-tropical depression front and is known as occluded front.
2007-10-24 23:58:13
·
answer #2
·
answered by Arasan 7
·
0⤊
0⤋
There are four major types of fronts:
Cold Front: A cold front's location is at the leading edge of the temperature drop off, which in an isotherm analysis would show up as the leading edge of the isotherm gradient, and it normally lies within a sharp surface trough. Cold fronts can move up to twice as fast and produce sharper changes in weather than warm fronts, since cold air is denser than warm air it rapidly replaces the warm air preceding the boundary. Cold fronts are typically accompanied by a narrow band of showers and thunderstorms. On weather maps, the surface position of the cold front is marked with the symbol of a blue line of triangles/spikes (pips) pointing in the direction of travel, and it is placed at the leading edge of the cooler air mass
Warm Fronts: Warm fronts are at the leading edge of the temperature rise, which is located on the equator-ward edge of the gradient in isotherms, and lie within broader troughs of low pressure than cold fronts. Warm fronts move more slowly than the cold front which usually follows due to the fact that cold air is more dense, and harder to remove from the earth's surface. This also forces temperature differences across warm fronts to be broader in scale. Clouds ahead of the warm front are mostly stratiform and rainfall gradually increases as the front approaches. Fog can also occur preceding a warm frontal passage. Clearing and warming is usually rapid after frontal passage. If the warm air mass is unstable, thunderstorms may be embedded among the stratiform clouds ahead of the front, and after frontal passage, thundershowers may continue. On weather maps, the surface location of a warm front is marked with a red line of half circles pointing in the direction of travel.
Stationary Front: A stationary front is a non-moving boundary between two air masses, neither of which is strong enough to replace the other. They tend to remain essentially in the same area for extended periods of time, usually moving in waves. There is normally a broad temperature gradient behind the boundary with more widely spaced isotherm packing. A wide variety of weather can be found along a stationary front, but usually clouds and prolonged precipitation are found there. Stationary fronts either dissipate after several days or devolve into shear lines, but can change into a cold or warm front if conditions aloft change. Stationary fronts are marked on weather maps with alternating red half-circles and blue spikes pointing in opposite directions, indicating no significant movement. When stationary fronts become smaller in scale, degenerating to a narrow zone where wind direction changes significantly over a relatively short distance, they become known as shear lines. If the shear line becomes active with thunderstorms, it may support formation of a tropical storm or a regeneration of the feature back into a stationary front. A shear line is depicted as a line of red dots and dashes.
Occluded Front: An occluded front is formed when a cold front overtakes a warm front. The cold and warm fronts curve naturally poleward into the point of occlusion, which is also known as the triple point in meteorology. It lies within a sharp trough, but the air mass behind the boundary can be either warm or cold. In a cold occlusion, the air mass overtaking the warm front is cooler than the cool air ahead of the warm front, and plows under both air masses. In a warm occlusion, the air mass overtaking the warm front is warmer than the cold air ahead of the warm front, and rides over the colder air mass while lifting the warm air. A wide variety of weather can be found along an occluded front, with thunderstorms possible, but usually their passage is associated with a drying of the air mass. Occluded fronts are indicated on a weather map by a purple line with alternating half-circles and triangles pointing in direction of travel. Occluded fronts usually form around mature low-pressure areas
2007-10-24 21:00:06
·
answer #3
·
answered by Anonymous
·
0⤊
0⤋