In light of the recent and potential hurricane events at the moment. I thought it may be a good idea to explain how hurricanes form and how they work. Just some information for those who are interested
Some of you may have noticed that all most all the world circular storms begin their life some where within the tropical and occasionally sub tropical areas of the Earth. The main driving factor or energy source that fuels a tropical cyclone/ hurricane, is latent heat released from the condensation of water. The reason for evaporation is mainly due to heating of the ocean from the sun.
Hurricanes and Cyclones can last for days and in some cases months, it all depends on the abundance of warm moist air and water vapor. When that is cut off, (more often than not when landfall is made), the storm begins to decay and lose its structure, eventually dying. You will probably notice that as Gustav crosses land, its winds will drop and it will lose its circular structure and eventually disperse.
Tropical Cyclones and Hurricanes are notorious for being erratic and its hard to predict movement. Several factors such as the coriolis effect and also the presence of moist of being pulled into the system can effect a storms trajectory. In the southern hemisphere, the coriolis effect usually flings storms to the southeast, while in the northern hemisphere, storms are usually flung to the northwest. This is why so many storms cross the coast in the gulf of Mexico. It must be noted though, that factors such as wind shear, combined with coriolis can actually work against the storm, and decaying it.
The are several stages that can be noted as a hurricane, cyclone or typhoon is nearing a particular location. Sequence is as follows
- The weather is clear and warm, with light winds from a non typical direction. The reason being, that winds on the outer edges of the storm descends gently compensating for updrafts in the storm
- The sky becomes overcast with high cirrus bands, or cirrostratus, radiating as arms from the centre of the storm. A slow steady drop in pressure levels, followed by a more quick, sharp drop will be observed. Rain will usually occur
- The winds will strengthen considerably as the inner core of the storm approaches. Intense showers and large isolated thunderstorms will, reduce visibility and may cause flooding
4.The wind will suddenly drop to calm and the sky may become clear, or only have high cloud visible, as the eye of the storm passes over the location.
- As the eye drifts on, the high winds return like the ones experienced before hand, but this time from the opposite direction to those earlier. Rain and thunderstorms resume. At this point, as the eye moves away, the barometer will start to rise slowly, then steeper and quickly
- The weather eventually clears, the winds die down. Rain may still be around, but usually light and patchy. The barometer returns to a higher pressure as the storm moves on or decays
So that’s just some of the basic information on hurricanes, typhoons and cyclones and I will be happy to answer any questions regarding them. There is plenty more in detail information available around to if anyone’s interested.
Just a final word, Gustav was nothing unusual for this part of the world. Apart from the Pacific region, the Gulf of Mexico is the most hurricane prone area in the world. Hurricanes have been and will continue to exist in these areas for years to come. All I can say to people in those areas is, don’t become complacent in the future