Hurricanes 101: What, Why & How

If you have glanced at the tv or scrolled through your social media feeds in the past few weeks, it would have been impossible to miss the plethora of news coverage on the recent hurricanes that have hit the United States and its territories. It goes without saying that these catastrophes have affected many lives and have created new worries that these intense tropical storms may become the “new normal”. Amongst these growing concerns, it becomes imperative to arm ourselves with knowledge of how these storms form, whether global warming influences their growing intensity, and how we can prepare for and adapt to these harrowing storms.

Colloquially referred to as hurricanes in the U.S., this weather phenomenon goes by many different names depending on which ocean it draws water from. When tropical storms form in the Atlantic and northern Pacific oceans, they are referred to as hurricanes and often land in the United States. In the northwestern Pacific, the same storms are referred to as typhoons and often land off the east coast of Asia, near Japan. In the Indian ocean, they are referred to as cyclones or cyclonic storms. Interestingly, the only requirement to be classified as a cyclone, hurricane, or typhoon is that the storm creates winds that are over 74 miles per hour. For this article, we will continue to refer to these storms as hurricanes.

Regardless of the name, each tropical storm begins the same way. Near the equator, the air and the surface of the ocean are very warm. During the summer months (roughly from May to November), aptly termed the hurricane season, hot air from the equator becomes moist as ocean water evaporates from the surface and rises. This warm, moist air turns into clouds in the atmosphere and as the earth continues to rotate on its axis, it spins the clouds into its characteristic circular pattern. Often, when hurricanes hit land, they carry with them many catastrophic outcomes.

First and foremost, the whirling clouds and rain can reach wind speeds of up to 150 miles per hour or more. This often causes quite a bit of initial wind damage and destruction. However, once hurricanes hit land, they begin to weaken and lose speed because they have lost their power source from the rising ocean water. In addition to the first hit of wind, hurricanes often bring an initial “storm surge”, which is a bulge of water that builds up at the head of the hurricane due to high wind speeds and causes most of the initial damage. Yet again, once the initial wave of water hits, the wind speeds slow and the storm begins to lose traction.

Interestingly, the only requirement to be classified as a cyclone, hurricane, or typhoon is that the storm creates winds that are over 74 miles per hour.

After these initial blasts of wind and water, the larger concern becomes the overwhelming rain that can fall from a hurricane’s massive clouds that lead to flash flooding. Due to this danger, it is often the hurricanes with slower wind speeds that cause the most damage. Slower hurricanes move in much slower and create a smaller initial hit, but also take significantly longer to move out and can dump enormous amounts of water on land. Recently hurricane Harvey demonstrated the overwhelming effects of this by dropping the greatest amount of rainfall for any storm over the last 120 years as rainfall continued for more than 5 days. Not to be outdone, Florida also experienced massive flooding due to hurricane Irma, where almost 16 inches of water fell and flooded areas that have never previously flooded. Billions of gallons of water were sucked from Florida’s bays, leaving them dried out and empty.

With the occurrence of these enormously devastating storms that are significantly worse than usual and closer together than one would expect, it is reasonable to wonder if these types of hurricanes will continue to occur and how climate change might have an effect. According to recent research, trends suggest that there may be a tendency towards fewer, more intense hurricanes as seen in hurricanes Harvey and Irma. Due to a warming climate, the atmosphere holds more water and the sea level continues to rise. These circumstances may suggest why the most recent hurricanes were wetter and rainier than in the past. However, it is notable that hurricane data is not nearly as complete and thorough and climate history and most of the research is based in the past 30 years. In addition, many of the trends have been predicted through model simulations. Models can be incredibly accurate predictors, but are not infallible. More research into the hurricanes and their correlations with climate change are required to produce solid predictions for the future. Regardless, this year has been devastating for many, costing people their homes and billions of dollars in damage for cities. Arming ourselves with knowledge and supporting each other is the only way to persevere through these tragedies.

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Cassandra Poulos is a senior majoring in Biology on a Pre-health track. She has conducted research in Diane Slusarski’s lab at the University of Iowa using zebrafish to investigate candidate genes for cataracts. In addition to her research, she is also a biology ambassador giving tours to prospective students. As the Editor-in-chief of Stemosphere, she hopes to bring science into the lives of as many people as possible.