What Causes Hurricanes?

With the event of Hurricane Katrina in 2005, hurricanes have moved to the forefront in the global consciousness as a devastating natural disaster.  It seems a new tropical storm is always brewing somewhere along a coast and wreaking havoc in the towns that line these coasts. So, it would be educational, and perhaps even life-saving to learn some basic information on what causes hurricanes.

Hurricanes originate in the tropics for one main reason – the perfect weather conditions. The two prerequisites for a hurricane are warm water and moist warm air. It all begins when rays from the sun heat the water surface to at least 80ºF (26.5ºC). This warms the air at the ocean surface which rises up, taking water in the form of vapor with it.

This warm moist air encounters cooler air above, and the water vapor condenses out and not only forms storm clouds and rain drops, but it releases latent heat energy which further warms the cooler air above which then begins to rise as well. As a result, more air from the water surface is drawn up and a cycle of heat exchange is created.

As air is heated, it rises up, further heating more air, and forming condensation in the form of rain drops from the vapor that rises with it. In about 12 hours, the air begins to rapidly circle counterclockwise (in the Northern Hemisphere. It circles clockwise in the Southern Hemisphere).

The heat exchange between the water surface and the atmosphere creates a spiraling wind pattern that has a calm center. To further exacerbate the situation, converging winds at the ocean's surface collide pushing even more water vapor upwards, increasing warm air circulation and the wind speeds.

In addition, high pressure air at high altitudes pull even more heat away from the storm center, cooling the rising air resulting in further condensation and a faster release of latent heat energy. At the same time, the high pressure air is pulled into the low-pressure center increasing the wind speeds.

It is interesting to note that hurricanes are structured like pinwheels. The thicker clouds are nearer the center and they thin out towards the outer edges.

Although there is a unanimous consensus on the formation of a hurricane, the scientific community largely disagrees on the cause of the temperature changes that create a hurricane. Some believe that it is directly tied to human activity on the planet (yes, we are back to global warming), while others attribute it to a natural environmental cycle.

Whatever the cause, hurricanes have definitely become more frequent and severe, and it is time natural disasters became a serious food for thought for everyone.

What Is a Hurricane?

Hurricane is a regional name for a tropical cyclone. Tropical cyclone is the generic name for a storm system that has a sizable low-pressure center and several thunderstorms that produce strong winds and heavy rain. If the wind speeds surpass 39 miles per hour (mph), they are called tropical storms and they are given a name (like Katrina, Ike, and Andrew).

Believe it or not, there is a very precise system that goes into naming tropical storms). It is only when the wind speeds reach up to 74 mph and above, that they are upgraded to the level of hurricane.

As stated, hurricane is a regional name. Other regions with the same storm conditions would be said to suffer a natural disaster by a different name, such as the town of San Juan Baňo in the Philippines that was struck by typhoon Ketsana in 2009.

There are five different names for these disastrous tropical storms:

• Hurricane (the North Atlantic Ocean, the Northeast Pacific Ocean east of the dateline, or the South Pacific Ocean east of 160E)
• Typhoon (the Northwest Pacific Ocean west of the dateline)
• Severe tropical cyclone (the Southwest Pacific Ocean west of 160E or Southeast Indian Ocean east of 90E)
• Severe cyclonic storms (the North Indian Ocean)
• Tropical cyclone (the Southwest Indian Ocean)