Changes in weather will depend on the position of the observer in relation to the cyclone passing overhead. If the cyclone passes the observer along the line ab, the weather observed will be somewhat different from that experienced along the line cd.
If the cyclone passes along ab, the observer is to the north of the centre of the cyclone. In this case, there is no warm sector or front. Therefore the weather conditions associated with warm or cold fronts are absent in this portion of the cyclone.
In this section the temperature remains cool during the passage of the cyclone. The pressure becomes progressively lower. Sky is overcast. In winter there are snow and icing storms. Since this portion of the cyclone contains occluded front which moves more slowly than cold or warm fronts, its influence is felt longer over the region.
ADVERTISEMENTS:
As regards cloud conditions, at first the sky is covered with cirrus clouds which gradually change into cirrostratus, altostratus and finally nimbus. In the beginning, the precipitation is light, but becomes heavier as the storm moves eastward.
Along ab, usually there is a broad region of light rains which result from the uplift of warm air above the cold air from the north. After the storm has passed, there is a gradual decrease in precipitation.
After rains have stopped, the nimbus clouds at lower levels are soon replaced by stratocumulus and alto-stratus. At high levels, the cirrostratus clouds make their appearance. However, with the rapid disappearance of the cirrostratus the sky becomes clear.
Areas located north of the centre of the storm have backing winds as is clear from the diagram. Backing winds denote the counterclockwise change in their direction.