Refer to figure.

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Mid Latitude Depression development

1. CYCLOGENESIS STAGE – this is known as the initial stage of the cyclone’s life cycle. In this stage, a boundary separates opposing fronts of cold and warm air. When an upper level disturbance moves over the front, it causes a wave to form.
Cyclonic shear begins to happen when the warm and cold fronts slide against each other => which generates the spinning motion characteristic of cyclones.

2. DEVELOPED/MATURE STAGE – during this stage, the wave formed during the initial phase grows as warm air replaces the space left behind by moving the cold front. The cold front moves faster than the warm front, intensifying the cyclonic circulation.

3. OCCLUDED STAGE - In the mid-latitude cyclone’s third stage, the denser cold front catches up with the warm front. Because the warm air isn’t dense enough to displace the cold air ahead of it, it shifts up and slides above the cold air in its path. This action eventually forms an occluded front, in which the wave transforms into a loop, which is narrower at its base and cuts off the supply of warm air.

4. DISSOLVING/ FRONTOLYSIS STAGE - The final stage of the cyclone occurs when the loop formed by the cold front boundary surrounding the low-pressure pocket of warm air closes. This cuts off the supply of warm moist air and the lifting force caused by the interaction between the cold and warm fronts. The loss of the convergence and uplift mechanisms cause the cyclone to dissolve, and the low pressure system gradually stabilizes.