Latent heat is simply heat released or absorbed by a substance (in this case, water vapor) as it changes its state. When water vapor condenses into liquid, it releases this heat into the surrounding atmosphere. The atmosphere around this condensation then warms.

Since warm air is less dense than cooler air, the warmer air takes up more space. This expansion of this air (red arrows) forces more air outside away from the center of the storm and the surface pressure (which is the weight of the air above the surface) decreases.

When the surface pressure decreases, a larger pressure gradient is formed, and more air converges towards the center of the storm. This creates more surface convergence and causes more warm moist surface air to rise above the surface. This air, as it cools, condenses into clouds. While it does this, it releases even more latent heat. This cycle continuously repeats itself ­ each time intensifying the storm until other factors, such as cool water, land, or high wind shear act to weaken it.