There are many hurricanes in the Bermuda Triangle because it is in a hurricane zone, with warmer waters feeding the formation of storms. Any tropical area has this property, and the Bermuda Triangle's reputation is mostly made up.

There aren't any magnetic anomalies in the triangle, even. Simply because it is in the tropics, the weather can be dangerous for ships and plane, and no current scientific evidence exists to show that the triangle is any different than any other tropical area. It's a very common myth, though, and a good plot point for science fiction movies.

It turns out that it actually doesn't. The Bermuda Triangle has stormy weather as a body of semi-tropical water, but it has about the same number of storms as another body of water does at similar latitude, and, for the amount of shipping going through it, it has a similar rate of wrecks as any similarly sized body of water at that latitude as well.

Actually, the Bermuda Triangle doesn't on average have more storms than any other tropical body of water. A lot of the stories surrounding the Bermuda Triangle were fabricated or exaggerated.

To answer your question about tropical storms in general: tropical storm formation typically requires very warm, large bodies of water, such as those found in what has been referred to as the Bermuda Triangle. Water from the surface of the ocean evaporates because of the high temperatures. The evaporated water, which exists in the form of a gas, rises from the ocean's surface because it is hot relative to the air above it (hot air rises, cool air sinks). As the hot air is rising, surrounding warm, moist air flows in and since the earth is rotating, air "curves" or "spirals" toward the center rather than travelling in a straight line. Hope this helps!