They can destroy buildings, bridges, and freight trains, and even blow the water out of a river or small lake, leaving it empty. They form as strong winds pick up moisture over warm surface waters of the tropical ocean and start to spin as a result of the rotation of the Earth. The spinning causes an upward spiral of massive clouds as air is pulled upward. Known as hurricanes in the Atlantic, typhoons in the Pacific, and cyclones in the Indian Ocean, tropical cyclones are most common during summer and autumn months when ocean temperatures are warmest. Storm surges can cause property damage and loss of life.
Some hurricanes produce torrential rains.
For example, Hurricane Mitch, which hit the Atlantic coast of Central America in October 1998, caused more than 10,000 deaths during the flooding and landslides that followed. Mitch, which caused extensive damage in Honduras and Nicaragua, was the deadliest hurricane to occur in the Western Hemisphere in at least 200 years. Some years produce more hurricanes than others. Some of the factors that influence hurricane formation in the North Atlantic include precipitation in western Africa and water temperatures in the eastern Pacific Ocean. A wetter than usual rainy season in the western Sahel region of Africa appears to translate into more hurricanes, as does a dissipation of ENSO, which results in cooler water temperatures in the Pacific.