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Figure 27- cold front occlusion and warm front occlusion Figure 28 – symbols used for Fronts
Cold front occlusion | Warm front occlusion |
Occurs when the cold air which overtakes the warm air is colder than the retreating cold air | Occurs when the retreating cold air mass is colder than the advancing cold air mass |
In the initial stage, weather system of the warm front persists. At the later stages the weather conditions resemble those of the cold front. | |
Overtaking cold airmass plows under both air masses | Advancing cold air being relatively less dense overrides the retreating cold air mass |
Table 6 – Occluded fronts – difference between cold front occlusion and warm front occlusion
7. Cyclones
The atmospheric disturbances which involve a closed circulation about a low pressure centre, anticlockwise in the northern atmosphere and clockwise in the southern hemisphere are called cyclones. They fall into the following two broad categories: (a) Extra-tropical and (b) tropical cyclones.