Sunday, March 18, 2007

"sahara dust"

So ya...the purple haze from yesterday's post is all here..

This morning the haze isn't as bad as it was yesterday thankfully, but its still there and we won't be seeing Montserrat today on the south side. "Sarah Dust" also known as African Dust comes across the Atlantic every year blanketing the region in haze. Many people think incorrectly that the haze has something to do with Montserrat's, but the world's most studied volcano, Soufriere, has nothing to do with it. What happens is that high winds blow massive quantities of dust from western and northern Africa up into the sky. Millions and millions of tons a year of it comes across the Atlantic passing through the Caribbean traveling on the same trade winds that brought the original European settlers here. The dust reaches the south-eastern part of the usa too. There is loads of info on all of this on the web these days and after googling "african dust" i came across many articles on it. Anyway, what most of them agree upon is that since the early 1970s the mass and content of the dust has changed dramatically. Yesterday there was yet another terrible report about glaciers melting, but equally scary is how the deserts are growing. Extreme droughts possibly to do with the "green house effect" as well as changing land and water use has resulted in more land losing its vegetation. Of course this results in more dust getting into the air, but that isn't the worst of it. Since the 1970's there has also been a change in the composition of the dust. There is now all kinds of pollutants contained inside the dust and many scientists are now attributing much of the decline in our coral reefs to this increase in african dust. It’s quite logical actually because we all know that when coral is covered with silt of any kind in can die, so with african dust filled with pesticides and all the other nasties covering the coral each year, it’s not hard to make the connection. Poor coral! There are so many things killing it off that i think much of it is gone forever. Sadly, i remember when i was a teenager just 15 years ago snorkeling on huge coral forests teaming with life. See the movie Finding Nemo....that's what the reef was like here back then. All of a sudden we had a few mega-hurricanes and most of the reef was gone. Many people blame the hurricanes which were stronger than Antigua had seen in over 2000 years (a fact that i will talk about another time), but the reef's decline wasn't just because of the storms. If you are interested in reading more then bookmark this link on coral and african dust.

I suppose it will take more time and study to find out all the negative effects of this increase in african dust, but there is at least one positive result. Kind of... Using satellite imagery, the NAOAA people predict when we in the Caribbean will get "african dust surges", and we actually know days in advance when it will be hazy. This is an image of dust coming off Africa.
Check here for more of these images. They have done many studies on the effects of the dust on our weather and have concluded without a doubt that increased levels of the dust can hinder hurricane formation which is wildly interesting to me. Considering the fact that due to "global warming" we are forecast to have more conducive conditions for extreme hurricane formation, it is also interesting that also due to global warming the increase in dust helps to deter these storms from forming. The way it works is that the dust doesn’t come across the Atlantic in a constant stream and instead comes in big waves almost like weather fronts. If good hurricane forming conditions and the dust appear in the same area, then water droplets inside the clouds become too heavy when mixed with the dust and fall out of the sky before they get a chance to become huge thunderstorms. The dust kills the storms before they get a chance to turn into hurricanes. There are many articles on all of this here if you are interested.
Other issues that you may not think about which are due to the dust have to do with the mess it makes. My boats are covered in brown clay like dust after weekends like this. I know that we will have to clean them tomorrow morning because of this hazy weekend.
I am glad i don't have to clean sails! Many of the yachts doing crossings come in with dirty sails and even aircraft have trouble on the leading edges of their equipment.
My eyes have given me more and more problems over the past few years and i sometimes wonder if it’s due to all the time i spend in the outdoors in contact with this increased dust. According to several studies, an increase in certain diseases can also be attributed to african dust. Great!...another thing to worry about right? If you are one of those people interested or worried about germs...check this out: Sorry:) There is another interesting health report on This one too.
Anyway, there is a hell of a lot interesting info to digest on the whole "Sahara dust" topic and i hope you found it as interesting as i said it would be. It’s a good thing it’s not all negative though. That thing about the hurricanes is gonna make me sleep better in the summer. One of the other cool things that can happen as a result of the dust is the sunsets.
They even have articles on that. The pics above are of cool dusty sunsets. The satellite one is of dust coming off Africa.