reasons for the increase or dissipation of hurricane strength

http://www.pbs.org/wgbh/nova/earth/hurricanes-climate.html

http://en.wikipedia.org/wiki/Tropical_cyclone

The increase or dissipation of hurricane strength can be influenced by several factors. These include:

1. Sea surface temperature: Warm ocean waters provide the energy needed for hurricanes to form and strengthen. When the sea surface temperatures are above 26.5°C (80°F), it becomes favorable for the formation and intensification of hurricanes.

2. Atmospheric conditions: Certain atmospheric conditions can either promote or inhibit hurricane development. These include low wind shear (the change in wind speed and direction with height) and sufficient moisture and instability in the atmosphere. High wind shear can disrupt the structure of a hurricane and prevent it from intensifying.

3. Coriolis effect: Hurricanes are formed due to the rotation of the Earth. The Coriolis effect, caused by this rotation, helps to form the distinct circular motion of a hurricane. The absence or weakening of the Coriolis effect can prevent the formation or dissipation of a hurricane.

4. Vertical wind structure: A favorable vertical wind structure allows hurricanes to develop and intensify. When there is a divergence of air at the upper levels of the atmosphere and convergence of air near the surface, it allows the cyclonic circulation to strengthen. Conversely, when there is strong wind shear and an unfavorable vertical wind structure, it can weaken or dissipate a hurricane.

5. Interaction with land masses: When hurricanes move over land, they lose their primary source of energy, which is warm ocean waters. As a result, they tend to weaken and may eventually dissipate. However, in some cases, interaction with land can also cause a hurricane to strengthen briefly if certain conditions are met.

It's important to note that the science behind hurricanes and their behavior is complex, and these factors interact in intricate ways. Additionally, climate change is believed to play a role in the intensification of hurricanes, but the full extent of its impact is still being studied.