Sahara dust… It’s a small world

I’ve been engrossed in some rather interesting books lately, so I guess I have taken a bit of a break from writing here. But I had to share something that I have always found fascinating – in the South, we have periods where dust from the Sahara Desert in Africa catches the trade winds and flows all the way over here. (Most of it lands in the Atlantic Ocean, however.)

These SAL events are powerful enough to shut down the formation of tropical storms across the Atlantic because the SAL spins in an anti-cyclonic (clockwise) manner like high-pressure systems. They cancel out the force of low-pressure systems that form hurricanes. I, for one, am looking forward to this period of relatively dry weather so I can finally get some garden chores done.

Did you know that the region known as the Sahara Desert alternates between an intense desert and a savanna over time? (And that has some fun implications for climate…)

For several hundred thousand years, the Sahara has alternated between desert and savanna grassland in a 20,000 year cycle caused by the precession of the Earth’s axis as it rotates around the Sun, which changes the location of the North African Monsoon. The area is next expected to become green in about 15,000 years (17,000 CE).

Here’s an article from MIT that discusses the climate cycles of the Sahara.

I first found myself reading about this phenomenon in reading about historical trade routes across Africa. Even in somewhat recent history, it was less difficult to navigate North Africa because it was a far less harsh environment.

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