A Hard Rain in a Dry Country

El Fuerte, Sinaloa, is at slightly more than 26 degrees North latitude and an elevation of only about 80 meters, so at this time of year the Sun is nearly directly overhead at noon, and it's hot. The Pig was hot. The Pig had been hot hundreds of kilometers North and 1200 meters higher in El Paso.

Walking around the plaza in the noonday sun, the Pig was sweating like a pig - or rather, sweating like a pig would sweat if a pig could sweat, which they can't. By the time he managed to stagger into the hotel's (shaded but outdoor and still sweltering) bar, he was as parched as the leafless semi-tropical forest all around.

When the P descended from the heights of the Sierra Madre on the Chepe he noted passing through a sequence of climate zones, from alpine pinon to tropical banana and palm, but as one approached El Fuerte, the landscape was dominated by a leafless and lifeless looking deciduous forest.

El Fuerte sits pretty squarely in the horse latitudes, that region where the hot air that rose in the intertropical convergence zone (ITCZ) comes back down, having been squeezed of its moisture along the way. That dry and descending air is quite effective at suppressing thunderstorm activity, which is why many of the world's deserts are similarly situated.

The ITCZ moves a bit with sun position, though, so like many such regions, El Fuerte has a rainy season that tends to fall in late July and August - the season following but lagging the sun position.

Weather of any sort being a fairly rare phenomenon in the P's home region, he was thrilled when distant rumbles of thunder heralded the approach of dark and nasty looking clouds. The storm arrived with gusty gusto, those gusts blowing leaves, tableclothes, umbrellas and similar items into the pool. A bit later rain arrived, and the thermometer dropped abruptly. There are storms like this in NM, but they only last ten minutes or so. This one lasted for hours, and the thatched roof of the bar proved little defense against horizontal rain, but we mostly stayed soaking up the welcome cold.

The next morning he took a train back up into the mountains, and almost every tree of that dessicated and gray forest was sprouting tiny green leaves or cheerful flowers. How do the roots get the water up to the growing sprouts so fast?