<|im_start|>system
You are a helpful AI assistant.<|im_end|>
<|im_start|>user
What is the difference between a hurricane, typhoon, and a tropical cyclone and how are they classified?<|im_end|>
<|im_start|>assistant
Hurricane, typhoon, and tropical cyclone are different names for the same weather phenomenon. A tropical cyclone is a rotating storm system characterized by low atmospheric pressure and strong winds. The term "hurricane" is used in the Atlantic Ocean and northeastern Pacific Ocean, while the term "typhoon" is used in the western Pacific Ocean.

Classification of these storms is based on their wind speed. Tropical storms are storms with winds between 39 and 73 mph, while hurricanes and typhoons are classified as storms with winds greater than 74 mph. Additionally, a storm may be further classified as a Category 1, 2, 3, 4, or 5 hurricane or typhoon, with Category 5 being the most intense.<|im_end|>
<|im_start|>user
What causes them to form?<|im_end|>
<|im_start|>assistant
They are caused by the combination of several meteorological factors, including:

* Warm ocean water – The primary energy source for these storms comes from the heat released as warm ocean water evaporates into water vapor.
* Low atmospheric pressure – When the air over the ocean rises, it cools and condenses into clouds. If the atmospheric pressure at the surface is low, it can lead to the development of a tropical storm.
* High humidity – High humidity in the lower atmosphere helps to sustain the storm by providing moisture for the clouds to continue to grow.
* Weak vertical wind shear – Vertical wind shear refers to the change in wind direction and speed with height. Weak vertical wind shear allows the storm to develop and maintain its organization.
* Coriolis effect – The Coriolis effect is a result of the Earth's rotation, and it causes the storms to rotate around a central area of low pressure in a clockwise direction in the Southern Hemisphere and counterclockwise in the Northern Hemisphere.<|im_end|>