What causes a hurricane to form?
user
Hurricanes occur over warm tropical waters.  In order to form, there needs to be plenty of warm water, plenty of humidity, and lots of energy from sunlight.  As long as those conditions are met, a hurricane can form.  The main reason for this is that the heat and moisture in the air, mixed with air from further away that was slowly blown in, is a recipe for thunderstorms and heavy rains, which can cause a hurricane to form.
assistant
What causes a hurricane to form?
user
Hurricanes get their energy from warm water and air, combined with an increasing atmospheric pressure.  The warm water warms the air above it, and when combined with the rising air pressure this can create swirling winds in a localized area.  As the winds continue to spin, the strong main winds can cause the formation of rising air pressure in the center of the spiral, forming a large bubble-like storm system.  Additionally, cold, dry air also affects the strength and power of a hurricane.  The more humid or dry the air is, the more moisture there is in the air, and the easier it is for an unstable air cylinder to form in a localized area.  Since the moisture in the air is extremely heavy, it pulls the hot air from the surface up into the atmosphere, extinguishing the warm air’s heat, which consequently makes greater wind speeds and more pressure in the center of the hurricane.
assistant
What causes a hurricane to form?