Mid-latitude cyclones dissipate because they are driven by the temperature contrast between the cold polar air and the warm tropical air. As the cyclone moves away from the polar region, the temperature contrast decreases, and the cyclone loses its energy source. Additionally, the cyclone is subject to friction from the land and sea, which further reduces its energy. Finally, the cyclone is subject to the Coriolis force, which causes it to move in a curved path and eventually dissipate.
