Right now should be the most intense hurricane season in the Atlantic Ocean. However, the ocean is quite calm.
The Atlantic hurricane season starts at the beginning of July and usually peaks around mid-September and subsides in early November. There are an average of two dozen named storms during the season.
Tropical storms In the Atlantic on average (1991–2021) per year:
However, the current hurricane season has been exceptionally quiet. So far, there have only been five named storms. Only the most recent of them, Danielle and Earl, reached hurricane status just over a week ago. They didn’t hit land.
It is particularly significant that no single named storm formed in the Atlantic during August. There have only been two such Augusts: the last time was 25 years ago in 1997 and before that in 1961, says, among other things AccuWeather (you are switching to another service).
Also, the previous year in which no named storms formed between the beginning of July and the end of August was 1941. By the end of August last year, there had already been ten named storms in the Atlantic.
This hurricane season was predicted to be normal or even slightly more active than normal. It is possible that storms will still develop later in the fall, but the quiet start has puzzled even the experts.
This year is also a La Niña year, when there are usually more hurricanes, because at that time the upper winds in the region are more favorable for the birth of hurricanes. In addition, the surface water of the Atlantic has been warm, so there would have been every chance for storms to form.
The reasons for the quiet season can only be guessed at. One explanation could be a dry air mass hanging over the West African region, which has reduced the moisture over the ocean.
A senior researcher speculates that Africa’s dry air is the cause, among other things Phil Klotzbach from Colorado State University, who is one of the leading hurricane modellers. (you switch to another service) According to him, this is also one of the reasons for the heat wave that has scorched southern Europe this summer.
Climate change is changing hurricanes
It is possible that we will not see as many hurricanes in the next few years. The La Niña phenomenon is thought to end already this coming winter, and there are fewer hurricanes in El Niño years.
In addition, climate change is thought to reduce the number of hurricanes.
– According to climate change scenarios, the number of tropical cyclones will not increase much in a changing climate, but they will intensify. According to scientists, the changing climate increases the number of slow-moving and rapidly intensifying storms. Slow-moving storms bring locally heavy rains and storm surges, explains ‘s meteorologist Anne Borgström.
The warming of the surface waters of the oceans brought about by climate change is therefore likely to fuel stronger tropical cyclones.
Especially when tropical storms enter the very warm waters of the Caribbean Sea, they intensify quickly and significantly before hitting land with their destructive forces. For example, Hurricane Ida developed last year in just a few days for this reason.
The rapid development of storms further complicates the evacuation of large cities along the US coast as forecasting becomes more difficult. In addition, sea level rise increases the damage caused by floods caused by individual hurricanes, while the biggest damages from hurricanes in general are caused by floodwaters.
Rainfall from hurricanes is also predicted to increase due to, among other things, increased air humidity. In the future, storms may also move a little further north, closer to the polar region.
The birth and death of storms
A low pressure circulating over a warm tropical sea can turn into a violent cyclone. Hurricanes originate from small thunderstorms at sea and they require warm sea water of 26 degrees.
Clusters of thunderclouds pile up and start circling the ring. This larger storm draws in moist, warm air from the ocean and gains more energy in its vortex. When developed, it is a massive spiral that brings with it, among other things, heavy rains, tidal waves and destructive winds.
When a hurricane drifts over land or into a cold sea area, its energy supply is cut off and the storm dies quickly.
The diameter of a hurricane is several hundreds of kilometers on average, and the eye of the storm in its center is about 30–60 km. There is a calm in the eye of the storm, but it is surrounded by strong winds that can exceed 70 m/s.
Why are hurricanes named?
When a tropical depression intensifies into a tropical storm, it is given a name. The storms are named so that there is no confusion in the warnings, as several storms may rage in the same sea area at the same time.
In the early 20th century, Australian meteorologists named hurricanes after politicians. During World War II, American military meteorologists named storms after their wives and girlfriends.
Nowadays, pre-agreed lists of names are used. The list of names in the hurricane area includes both women’s and men’s names. Six alphabetical lists are used in the hurricane zone. Every year we start from the beginning of a new list – we return to the same list every seven years.
Storms that caused a lot of destruction, such as Katarina 2005 and Iota 2020, are always removed from the lists.
In active tornado years, the name lists may run out. Before, they switched to using Greek letters, but starting with the 2021 season, a fixed, additional list has been used.
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