Giant dust cloud will cover Cayman
The Caribbean region is being immersed by an outbreak of dust from the Sahara Desert which might reach the Gulf of Mexico and parts of the United States next week. Residents of the Cayman Islands can expect to see hazy skies this weekend caused by the giant dust cloud. It is normal for dust clouds to cross the Atlantic at this time of the year and it is not necessarily a bad thing because they generally inhibit tropical wave development, so hurricanes are less likely to form.
The dust cloud, identified as GOES-16, started from the coast of West Africa and will travel 5,000 miles across the Atlantic. There have been several smaller pulses of dust this season, but this plume is the largest yet.
These waves of sand and particulate matter are known as the Saharan Air Layer, which typically form from late spring through early fall, peaking in activity in June and July, and declining in August. They regularly move off the coast of Africa every 3-5 days in a layer between 5,000 and 18,000 feet above the sea surface and can cover an area as large as the United States.
The air in these plumes of dust is quite dry and warm, usually containing about 50 percent of the moisture content of the surrounding air over the Tropical Atlantic Ocean. This dry and warm air helps to inhibit thunderstorm development through suppressing updrafts and accelerating downdrafts. The warm air in the dust layer creates a strong temperature inversion, which suppresses the updrafts needed to maintain shower and thunderstorm activity. The dry air also aides in tearing apart tropical cyclone development.
Fewer thunderstorms typically mean lower chances for tropical systems to develop, but storms have survived large plumes of dust in the past so, each situation has to be assessed independently.
These plumes can also make sunsets much more colourful when the dust is thick in the air, since the increase in particulate matter leads to additional scattering of visible light. Cayman Islanders may see an increase in colours this Father’s Day weekend, while many states along the Gulf Coast could see similar effects through much of next week.
Among other benefits, these plumes can have negative impacts as well, including reducing air quality. They can also lead to toxic algae outbreaks in the Gulf of Mexico.
The dust can also cause toxic algal blooms in the Gulf of Mexico, according to NASA.
The Hurricane Research Division in Florida said the Saharan Air Layer is typically located between 5,000 and 20,000 feet above the Earth's surface and blown between 6,500 and 14,500 feet.
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