Soggy Equator
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Think of the equator and what comes to mind? Heat, likely, since the sun sends its rays directly at the earth's bulging waistline all year round. Hi. I'm Bryan Yeaton and this is The Weather Notebook.

There is another defining element of the equator. Rainfall. Lots of rainfall. The most persistently rainy places in the world are looped around the equator like a 25,000 mile belt of sponges. Look at a time lapse film clip of global cloud patterns and the equator is unmistakable for the ring of gray that constantly forms and re-forms around it.

The equator runs the world's most successful rain brewery because it has the two basic precip ingredients in an abundant supply: high humidity and converging surface winds. Prevailing air currents from the northern and southern hemispheres collide at the earth's mid-section, and the collision forces the air to go up. Rising warm air saturated with humidity is the classic formula for rain - and that's what the equator is all about meteorologically. Which is not to say that heavy rain is limited to the equator at 0 degrees latitude. At a latitude of 20 degrees South, the town of Cilaos on an island east of Madagascar is the world record holder for the rainiest day ever recorded--73.62 inches of rain on March 16, 1952. And just to prove that this was not a freak occurrence, nearby Grand Ilet racked up 46 inches of rain in 12 hours on January 26, 1980. That's five more inches than Boston averages in a year!

Thanks today to Seattle writer David Laskin. The Weather Notebook is a production of the Mount Washington Observatory, with support from the National Science Foundation.