The evolution of a hurricane is a chain of events that occurs in rapid succession. It begins with a low pressure area, or centre, that forms over the warm waters of the tropics and is known as a tropical depression. Once it reaches moderate strength, the National Hurricane Centre (NHC) classifies it as a category one storm on the Saffir-Simpson Hurricane Scale (SSHS). As these systems continue to intensify, wind shear reduces their ability to gain strength. As such, many of them weaken and eventually dissipate back into the atmosphere before reaching land. However, some are able to intensify again inland once they exit the coastal environment.
These strengthening hurricanes are known as recurving hurricanes. Over time, more intense storms become more common because their energy source — warm water — continues to fuel them. The average size of these storms also increasing due to rising ocean temperatures exacerbated by climate change. As a result, they are becoming more destructive due to their increased size and strength.
What is still considered a typhoon?
Typhoons are tropical cyclones that develop over tropical waters but do not have an organized centre of circulation. They are classified on the SSHS based on wind speed and must have maximum sustained winds above . In order to be considered a tropical storm, the winds must be sustained for at least 36 hours. If a tropical storm is able to make landfall, it is reclassified as a hurricane. Typhoons are caused by the warmer waters of the tropical Pacific Ocean and Indian Ocean intersecting with the westerly winds of the tropical air currents. These conflicting air forces drive the warm waters toward the cooler of the two and create the conditions for tropical development. However, these storms are extremely difficult to track due to their unpredictability and small size.
What is a category 3 or higher hurricane?
When the sustained winds of a hurricane reach Category 3 intensity, it is considered a major hurricane. Category 3 hurricanes are very strong with maximum sustained winds of 111 to 130 miles per hour. These winds are strong enough to cause extensive damage to buildings and cause extensive flooding. The strongest hurricanes are known as major hurricanes. These storms develop over the warm waters of the Atlantic Ocean and, because they originate over land, they must contend with much higher temperatures. As a result, they have developed into a much more powerful and destructive type of storm.
How will climate change affect hurricanes?
Climate change is expected to increase the intensity of tropical cyclones. The projected increase in intensity is due to a warmer tropical Atlantic Ocean, which leads to an increased presence of wind shear, and a higher frequency of storms that are able to remain organized over a sustained period of time. Due to a warmer tropical Atlantic, storms are able to maintain a more organized structure. However, a warmer tropical Atlantic Ocean also leads to more evaporation, which in turn leads to more intense hurricanes by increasing the latent heat of evaporation from the ocean. Another result of a warmer tropical Atlantic is an increase in heavy rain events.
Rising ocean temperatures fuel more destructive hurricanes
A 2013 study published in Nature found that the power of hurricanes is largely determined by the temperature of the water in which they form. When water in the tropical oceans is warmer than the average temperature, it is more likely to fuel disturbances that lead to the formation of tropical cyclones. The warmer water in the tropical Atlantic Ocean has risen by about 3 degrees Fahrenheit since the 1950s. This increase in temperature has allowed the water to expand further into the ocean and thereby expand the tropical water system. The overall effect of this increase in ocean temperatures is an increase in the size and intensity of tropical storms.
Super typhoons and extreme storms
Super typhoons are extremely powerful storms that form in the Pacific Ocean and often peak in intensity between Category 5 and 6. In order to be considered a super typhoon, the sustained wind speed must be at least . A super typhoon is the most powerful type of tropical storm and is generally associated with a large amount of rainfall. Super typhoons are becoming more common in the world’s oceans due to climate change. Extreme storms are those that are exceptionally strong and cause severe damage. A severe storm is a tropical cyclone that has sustained wind speeds of at least 155 miles per hour or a minimum central pressure of 960 millibars.
Hurricanes are likely to become stronger and more frequent as the Earth’s climate warms. Sea levels are rising as well, which could cause saltwater to infiltrate into coastal areas and increase the risk of flooding. Sea levels could even rise by up to 4 feet by the end of the century, which would put many coastal communities in danger. Hurricane damage is also likely to become more destructive due to rising ocean temperatures. Rising ocean temperatures fuel more destructive hurricanes, and they are becoming more common as the Earth’s climate warms.
Featured image courtesy of: NBC News
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