vigorously drives the warm air ahead of it aloft. Notice in Figure 2.5 that the edge of a cold front is very steep when compared to the warm front in Figure 2.4. Once the warm air begins to lift along the cold front, adiabatic cooling starts and vapour condenses, forming clouds. Because the air rises rapidly, it quickly cools adiabatically, which means that large amounts of latent heat energy are rapidly released as the water condenses. As a result, rainfall is intense and of short duration. If sufficient moisture is present and enough latent heat is quickly released, an intense can form, with the latent heat being the fuel for its thunderstorm development. Fig. 2.5: Uplift of air along a cold front Table 2.1: Weather conditions associated with warm and cold fronts Weather Warm Front Cold Front condition Before the At the time of After the Before At the time After the Passing of Front Passing of Front the of Front Passing of Front Passing Front of Front Temperature Warming Warmer then Cooling Cold and Cool Warm suddenly levelling off suddenly getting colder Atmospheric Slight rise Levelling Decreasing Increasing Pressure Levelling off followed by a off then steadily steadily decrease steadily increasing Heavy rain Precipitation Showers, or snow, Showers then snow, sleet Light drizzle None Showers hail clearing or drizzle sometimes Clouds Cirrus, Clearing with cirrostratus, Cirrus Cumulus Stratus, scattered stratus, altostratus, and and sometimes sometimes Cumulus cumulonimbus scattered and then cumulonimbus stratus : Occluded fronts are formed when cold and warm fronts merge. are produced when a fast moving catches and overtakes a slower moving . Two types of occluded fronts are generally recognized. A cold type occluded front occurs when the air behind the front is colder than the air ahead of the front. When the air behind the front is warmer than the air ahead of the front a is produced. Warm type occlusions are common on the warm type occluded front west coast of continents and generally form when maritime polar air collides with continental polar or arctic air.
vigorously drives the warm air ahead of it aloft. Notice in Figure 2.5 that the edge of a cold front is very steep when compared to the warm front in Figure 2.4. Once the warm air begins to lift along the cold front, adiabatic cooling starts and vapour condenses, forming clouds. Because the air rises rapidly, it quickly cools adiabatically, which means that large amounts of latent heat energy are rapidly released as the water condenses. As a result, rainfall is intense and of short duration. If sufficient moisture is present and enough latent heat is quickly released, an intense thunderstorm can form, with the latent heat being the fuel for its development. Fig. 2.5: Uplift of air along a cold front Table 2.1: Weather conditions associated with warm and cold fronts Weather condition Warm Front Cold Front Before the Passing of Front At the time of Front After the Passing of Front Before the Passing of Front At the time of Front After the Passing of Front Temperature Cool Warming suddenly Warmer then levelling off Warm Cooling suddenly Cold and getting colder Atmospheric Pressure Decreasing steadily Levelling off Slight rise followed by a decrease steadily Levelling off then increasing Increasing steadily Precipitation Showers, snow, sleet or drizzle Light drizzle None Showers Heavy rain or snow, hail sometimes Showers then clearing Clouds Cirrus, cirrostratus, altostratus, and then stratus Stratus, sometimes cumulonimbus Clearing with scattered stratus, sometimes scattered cumulonimbus Cirrus and Cumulus and Cumulus : Occluded fronts are formed when cold and warm fronts merge. are produced when a fast moving catches and overtakes a slower moving . Two types of occluded fronts are generally recognized. A cold type occluded front occurs when the air behind the front is colder than the air ahead of the front. When the air behind the front is warmer than the air ahead of the front a warm type occluded front is produced. Warm type occlusions are common on the west coast of continents and generally form when maritime polar air collides with continental polar or arctic air.