Part 1: Understanding Hurricanes

With Harvey and Irma battering anything in their path, a question has to be asked: are these brutal hurricanes becoming more frequent? Before we can answer this question however, we need to understand exactly what a hurricane is and what causes this destructive weather pattern.

This is Part 1 of the Hurricane series.

This article will explain:

  1. What is a hurricane?
  2. What are the causes?
  3. When does a tropical storm become a hurricane?
  4. What are the different sections of a hurricane?
  5. When is hurricane season?
  6. How is the scale of a hurricane measured?
  7. What causes the damage?
What is a hurricane?

Defined as a tropical storm with violent winds, a hurricane is the same weather system as a cyclone or a typhoon. The main difference between these three is their location. A typhoon occurs in the Northwest Pacific whereas a cyclone occurs in the South Pacific. A hurricane is a tropical storm in the Atlantic and North-East Pacific.

What are the causes?
Warm air from tropical waters causes thunderstorms by rising to high altitudes and creating an area of low pressure close the to the oceans surface. Air from the surrounding areas floods in to equalise the pressure difference. Due to the Earth’s rotation, cyclones south of the equator spin clockwise whereas cyclones north of the equator spin counter-clockwise! For an awesome explanation of why this happens, check out this answer on Quora.
When does a tropical storm become a hurricane?

According to the National Hurricane Centre, when the sustained windspeed reaches a certain threshold (above 73mph) a tropical storm becomes a hurricane. To then be classed as a major hurricane, the storm needs to have sustained windspeed of greater than 111mph.

What are the different elements of a hurricane?
A hurricane is made up of three sections: the eye, the eye wall and the spiral rain bands.
At the centre of the storm the eye is relatively calm. There is little to no rain and it is the warmest part of the storm.
The eye wall encircles the eye and has the strongest winds. It also contains the most rain. This is the strongest part of the storm and causes the most damage as it passes.
The spiral rain bands are on the edges of the storm, sometimes trailing inwards for hundreds of miles. These can still have strong, dangerous winds but are not as powerful as those in the eye wall.
 
When is hurricane season?

Hurricane season in the Atlantic stretches from June 1st until November the 30th, with the peak of the season being September 10th.

How is the scale of a hurricane measured?

To measure the intensity of a tropical storm, the  Saffir–Simpson hurricane wind scale (SSHWS) is used. This sorts storms into 5 categories depending on wind speeds. Created by Herb Saffir and Bob Simpson, this tool has been widely used to predict the damage done to property by the various levels of hurricanes. For more detailed explanation of what damage can be expected from each category, have a look at the table on the National Hurricane Centre’s website.

What causes the damage?

The power and energy release by this massive weather system is hard to imagine. A force 5 hurricane such has sustained wind speeds of over 155 MPH, which can rip houses to shreds. Couple this with billions of gallons of rain that falls in a short space of time and our concrete jungles can quickly become overwhelmed. Damage is caused by flooding from rainwater as well as huge torrents of water coming off the ocean in a storm surge.

Damage is caused by:

  • High Winds
  • Intense Rainwater
  • Storm Surge
Thank you for taking the time to read this article. If you enjoyed this and want to read more, have a look at the related posts!

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