Extra Tropical Cyclones
Extra tropical cyclones occur in the mid and high latitudes beyond the tropics. They develop along the polar front and are influenced by the dynamics of differing air masses. Initially, the front remains stationary until a drop in pressure prompts warm air from the south to move northwards and cold air from the north to move southwards, creating an anticlockwise cyclonic circulation in the Northern Hemisphere.
Key Features
- Structure: An extra tropical cyclone features both a warm front and a cold front, with warm air wedged between colder air sectors, leading to various precipitation forms as the warm air rises.
- Lifecycle: The cold front typically moves faster than the warm front, overtaking it, leading to occlusion where warm air is completely lifted above the surface, resulting in the dissipation of the cyclone.
- Differences from Tropical Cyclones: While tropical cyclones form solely over warm oceans and have no pronounced frontal systems, extra tropical cyclones can develop over land or sea and possess a unique frontal structure. Tropical cyclones, marked by higher wind speeds and destruction, move from east to west, contrasting with the west-east movement of extra tropical cyclones.
These phenomena significantly affect weather patterns across vast areas, highlighting the importance of understanding their dynamics.