How does a cyclone happen? Well, Only tropical cyclones that form over the Atlantic Ocean or eastern Pacific Ocean are called "hurricanes." Whatever they are called, tropical cyclones all form the same way. Tropical cyclones are like giant engines that use warm, moist air as fuel. That is why they form, only over warm ocean waters near the equator. Hurricanes are the most violent storms on Earth. They form near the equator over warm ocean waters. Actually, the term hurricane is used only for the large storms that form over the Atlantic Ocean or eastern Pacific Ocean.