2. The second force is the Coriolis force, named after Gaspard Coriolis, a 19th century French engineer and mathematician. This is the force that affects any spinning object such as the earth. It means that the air is forced to move toward the center of the low air pressure area in a clockwise spiral in the southern hemisphere and counterclockwise in the northern hemisphere. The result is the circular, cyclonic patterns seen on weather maps.
3. In parts of the world close to the equator, these cyclonic patterns may become tropical cyclones. These are among the most powerful and destructive phenomena on earth. A major cyclone may release energy at the rate equal to 25 hydrogen bombs every second. In the eastern hemisphere, tropical cyclones are called typhoons, from the Chinese ‘tai fung’, and in the west they are known as hurricanes.
4. Seawater needs to be at a temperature of at least 270C for a tropical cyclone to form. Water vapor condenses into clouds and the air begins to rotate. The atmospheric pressure falls quickly and the wind speeds increase. Around the eye-the center- of the cyclone, wind can circulate at 250kilometres per hour; a gust in one especially violent cyclone reached over 300 kilometers per hour. However, in the eye itself, the air is still and bright. Over four to eight days, the very thick, whirling cloud system can grow to 1500 kilometers in diameter, with an eye of 5 to 15 kilometers. Fortunately, storms like these are relatively rare, and