|An Anvil Cloud that often proceeds a Monsoonal thunderstorm. An Anvil Cloud is a type of cumulus cloud.|
|Haboob dust storm in Phoenix, Arizona. Picture from Wikipedia.|
Haboobs are very important soil formation events. All of the dust and clay within these dust storms has to fall on soil somewhere. Dusts from these storms is deposited on soils and enriches them with magnesium, calcium, iron, and of course clay. After these things are deposited on soil surfaces, rain water will carry them deeper into the soil. After thousands of years of this happening iron stains the soil red, magnesium stains rocks on the surface black, calcium forms a rock-like layer called caliche about 2-3 feet deep, and clay forms a dense clay-rich horizon just above the caliche called an argillic (Click here for more info from an prior blog entry). Caliche and argillic soils are extremely important in determining what types of plants live in a particular locations. Some plants prefer soils with caliche or argillics while others do not. More on that another time though.
The rains should come to nearly the whole Sonoran Desert within the next few weeks or so. That is, at least the eastern portion. Normally Tucson receives about six inches of rain, Phoenix three, and Yuma less than one during Monsoon season. But actually amounts vary from year to year. In Phoenix I have seen years with only a half inch or so, and other years with nine inches. It has been a few years since we have had a really good amount of rain during Monsoons season, maybe that means this will be a good one!