- The temperate cyclones occur in the mid latitude of both the hemisphere.
- These cyclones are born along the polar front, particularly in the region of Icelandic and Aleutian sub –polar low pressure areas in the northern hemisphere.
Development and strengthening of mid latitude wave cyclone is known as cyclogenesis. This is called the polar front theory, given by Bjerkness in 1918. On an average, a temperate cyclone takes 3-10 days to progress through the stages of development.
‘life cycle of cyclone’
The period of cyclone from its inception to its termination is called the ‘life cycle of cyclone’ which is completed through six successive stages.
Stage A: the first stage involves the convergence of two air masses of contrasting physical properties and direction.
Stage B: it is called ‘incipient stage’ during which the warm and cold air masses penetrate into the territories of each other.
Stage C: it is mature when the cyclone is fully developed and isobars become almost circular.
Stage D: warm sector is narrowed in extent due to advancement of cold front at a faster rate than a warm front, and cold front comes nearer to warm front.
Stage E: this stage starts with the occlusion of cyclone when the advancing cold front finally overtakes the warm front and occluded front is formed.
Stage F: in the final stage, warm sector completely disappears, occluded front is eliminated and ultimately cyclone dies out.
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