When the winds in the rotating storm reach 39 mph, the storm is called a "tropical storm. Tropical cyclones usually weaken when they hit land, because they are no longer being "fed" by the energy from the warm ocean waters. However, they often move far inland, dumping many inches of rain and causing lots of wind damage before they die out completely.
The two GOES satellites keep their eyes on hurricanes from far above Earth's surface—22, miles above, to be exact! Learn more about this kind of orbit. These satellites, built by NASA and operated by the National Oceanic and Atmospheric Administration NOAA , save lives by helping weather forecasters predict and warn people where and when these severe storms will hit land.
Our World: What is a Hurricane? Here is a movie of Hurricane Katrina, which struck the coast of Louisiana, Alabama and Mississippi on August 29, , as a Category 3. This movie was made from images taken by the GOES weather satellite.
In the movie you can see the storm starting to form in the Atlantic on August 24 and becoming more and more organized as it moves over the warm waters of the Gulf of Mexico. How Do Hurricanes Form? Hurricane Fran. Image made from GOES satellite data. Click to view movie.
Therefore, biodiversity might sometimes be diminished due to typhoons in the short term, but typhoons might also be effective in enhancing biodiversity in the long term.
Rather than a direct influence of typhoons, changes in water environments which generate typhoons are more serious. As I answered in Question 1, the temperature increase of the sea surface is a factor generating a lot of typhoons.
In fact, such a temperature increase diminishes biodiversity in oceans and lakes. Temperature increases affect living things, but the more important factor diminishing biodiversity is that nutrients in deep water are not transported upward when the temperature gradient increases in a vertical direction. Biodiversity around the water surface, such as in the Pacific Ocean or Lake Biwa , is being lost in this way.
Typhoons sometimes inflict immense damage on human lives. Are typhoons necessary for ecosystems? Not just with typhoons but in general, low pressures play an important role in water circulation on earth. If there is no low pressure, vapor will not be transported upward. As a result, it will not rain, and desertification will be accelerated in desert areas. Most notably, the East Asian monsoonal region receives a great amount of fluid replacement from the Tropics thanks to the occurrence of seasonal typhoons.
Also, strong wind events strongly mix sediments as well as coastal areas or lakes, increasing oxygen availability. Anoxic sediments and deep waters are oxidized by storm events and new habitats will be created for living things. In addition, biological species living in upper reaches of streams are transported downstream, or seeds are transported to remote places by strong winds. These lead to enlarging the reproduction areas of living things.
Typhoons bring us disasters, but they can be an external force for creating new living environments for other living things. Based on the increasing average wind speeds at the center of a typhoon that are sustained for a period of 10 minutes, typhoons may be classified into 6 stages, from the least powerful to the most powerful forms, as follows:.
Tropical disturbances forming over the warm tropical waters of oceans near the tropics lead to the formation of typhoons. As low level winds flow into the regions of such disturbances, these winds absorb moisture and energy from the ocean and rise upwards. The absorbed energy is lost in the form of heat, warming the air above the ocean. As warm air is less dense, it rises, and colder air from the surroundings is attracted into the void created by the rising warmer air.
This air again absorbs moisture and energy from the ocean, again releasing heat as it rises up. Thus, a column of warm, moist air is created above the ocean, and this is known as a tropical depression. As the resulting drop in atmospheric pressure keeps intensifying, winds with ever greater speeds are attracted to the depression, and soon a tropical cyclone may be born. When the wind speeds at the center of such storms rise above a threshold value of kilometers per hour, the storms are then officially known as typhoons.
After they are formed, these typhoons tend to travel following either one of three types of paths: a straight track, a parabolic recurving track, and a northward track, each affecting any land that falls in their paths of movement.
These tropical cyclones frequently originate in the northwestern Pacific Ocean, usually in the tropical seas around the Caroline Islands and the Philippines , and occasionally also arise from the South China Sea. Taiwan , Japan , the Philippines, and China are the largest countries that are most affected by typhoons. Although the U.
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