Though Northern Hemisphere's hurricane season officially started on June 1st, this year had been relatively peaceful, until this week when Irene, a category 3 hurricane stormed across the Atlantic, wreaking havoc on the Caribbean Islands before moving on to the East Coast of the United States.
While the hardest hit was North Carolina, Irene's fury continued all the way to New York City where it caused massive flooding and left millions of people without power. And, while the worst is over, Irene is not done yet. Downgraded to a tropical storm, she is expected to bring some heavy downpour to the Canadian states of New Brunswick and Nova Scotia, before finally petering out.
So what causes these unstoppable acts of nature? In this article we go behind the scenes to examine how and why hurricanes happen and, if there is anything we can do to stop them.
While Scientists have been studying hurricanes for only the last one hundred years, there is evidence that these powerful storms have been going on for much longer. In fact, the name hurricane is thought to have evolved from the word 'Hurakan' - One of the gods of the ancient Mayan civilization that inhabited Mexicoaround 900 AD. The Mayans believed that Hurakan caused these storms by blowing his breath across the water. In 1400 AD the Carib Indians, who lived in the West Indies islands re-named the storms 'Hurican', or god of evil.
What Are Hurricanes?
Hurricanes also known as cyclones in some parts of the world, are super powerful storms, which gain momentum from winds that help them blow in at speeds ranging from 75 to 225mph, resulting in massive destruction when they hit land.
How Do They Occur?
For hurricanes to occur, the ocean temperatures must be at least 80°Fahrenheit and the atmosphere around it, saturated with moisture. Also, the winds must be blowing in the same direction and the same speed to force the air upward from the surface of the ocean.
What Happens Then?
The warm water creates low-pressure air, causing it to rise. As the air rises, it collects moisture-forming thunderclouds. Meanwhile, cool air displaces the empty space created by the warm air that has risen. As the warm air condenses, it produces even more heat and rises even faster, causing more cold air to rush in. This increases the intensity of the storm. As the hurricane winds rotate, they accumulate water in the center of the storm. This water, called the storm surge, is the most deadly part of the hurricane, because it dumps into any landmass it hits, causing floods and devastation. The bigger the storm surge, the more powerful the hurricane.
The Corriolis Effect
When a hurricanes first begins, the rising winds blow in towards the center of the storm. However, as it grows, it gets impacted by what is known as the 'Corriolis Effect'. This is when a force, in this case the Earth's rotation around its own axis, deflects objects on one side. So, while the hurricane is attempting to going straight, the Earth's movement causes it to deflect to the right, forcing it to go counter-clockwise, in the Northern Hemisphere and clockwise in the Southern Hemisphere.
Why does each Hurricane have a name?
Hurricanes are given names, so that scientists can track the storms from start to finish. In the fifties, hurricanes were named after the phonic alphabet, like Able, Baker etc. From 1953-1979, the US Weather Bureau decided to shift to only women's names. Since then, they have alternated between male and female names and now have six different name lists that they alternate each year. If a hurricane causes real major devastation, like Katrina did to New Orleans in 2005 , the name is replaced with another name and never used again.
What can we do to stop them?
Unfortunately, not much. In the past, scientists have tried various inventions to weaken these storms. But they gave up in the 1960's after realizing that the weather patterns were too large to affect. Instead, they changed their focus to understanding how hurricanes form and move, so that they could predict their timing and intensity with greater accuracy. But like other acts of nature, this too remains an inexact science - One that is neither completely predictable nor controllable.
What do the hurricane categories mean?
The hurricane categories, which range from 1-5, are simply a way to gauge their intensity, with 5 being the worst.
Since the peak of the hurricane season is not until end of September, there will probably be a few more big storms this year - But hopefully, the worst is over and while Irene did cause about $7 billion USD worth of property damage, it's toll on humans was relatively low, with about 27 people known to have perished so far.
Resources: wikipedia.org, weatherwhizkids.com, sciencedaily.com, abcnews.com