Curiosity About the Dry Islands
 

Some of the islands in the Caribbean/Atlantic region are notorious for being dry. In the Bahamas, as one moves from NW to SE approaching the Turks & Caicos, one goes from pine, more green islands to the semi-arid scrub of Inagua and Grand Turk. Equally in the Caribbean, you have lush islands such as St. Lucia and very dry islands like Aruba and Los Roques.<BR><BR>Obviously some of the islands get more rainfall than others. However, given that all the islands are surrounded by water (the Caribbean or Atlantic) which would evaporate due to warm temperatures and form clouds (no?), it seems counterintuitive to me that some islands would get so little rainfall as to be arid (on Grand Turk for example, cacti are widespread). I imagine it has something to do with wind patterns but I was curious if anyone had an explanation for this.<BR><BR>Cheers DAN

You will find the mountainous islands lush, and the flat islands, like the ones you mentioned, dry. The mountains cause the moisture from the northeast trade winds off the ocean to condense and form rain clouds. Even on the mountainous islands, there are parts which are desert-like. Those areas are mainly on the south, or southwest part of the island, in the "shadow" of the mountains. Hope this helps.

Thanks for your explanation Brian; that makes a lot of sense. When I think of the lush islands, they have mountains without exception: Saba, Dominica, Grenada, St. Vincent, Guadeloupe, Martinique, St. Lucia. This doesn't however explain the increasing dryness as one moves from the northwestern Bahamian islands to the southeastern ones, since these all are mostly flat. Maybe this is the change from a more temperate to a more tropical climate as one moves south?<BR><BR>Thanks again Brian; your explanation does correlate with most islands I can think of. DAN

Dan, <BR><BR>As for the northern Bahamas, I would guess that their weather is influenced by their location near the mainland US and by the Gulf Stream. Also, as you move north out of the tropics, the air becomes cooler and the trade winds become less of a factor.