How does "latent heat" help a huricane grow?
Hurricanes are a fascinating (and horribly destructive) force of nature, but the factors that help create them are pretty well known. "Latent heat" is one of those factors. I'll try to give you an overview of how this works:
Water holds heat pretty well, as I'm sure you've seen if you've ever waited for a hot cup of coffee or a scalding bowl of soup to cool. The ocean is like that, too. The water there holds a pretty stable temperature most of the time because it's hard to change the temperature of that much water.
When the water in the ocean evaporates it takes heat with it. This draws heat energy out of the ocean because this evaporation is warm and moist and the water replacing it (from rivers and rain and such) may not be. It's sort of similar to how sweat works, evaporating water off your skin and drawing away heat.
This moist air can stay around and turn into clouds or fog. Most of the time it seems to just be blown away by the wind. The problem happens if the air above the ocean is calm and there is no wind to blow the moist air around. The clouds build, the heat builds, and the amount of water in the air builds.
All this heat, among other factors, creates an area of low barometric pressure. If you've ever let the air out of a balloon you know that areas of high pressure like to move to areas of low pressure, so air from the surrounding areas (under higher pressure) begins to move in. It does so in a spiraling sort of way toward the center, like water going down a drain.
This influx of moving air causes more evaporation of the (warmer) ocean water, which just fuels the cycle by keeping the low-pressure system going. Instead of this "fuel" being blown apart or over land to ruin picnics with rain, it becomes trapped in the spiral and makes things worse.
Latent heat, then, is the "fuel" that drives hurricanes.