Invasion of the water molecules

At least more of them….   Overnight (take a look here), the dewpoint temperature, a measure of how much frost would build up in your refrigerator freezer and/or drip down the walls of it if you left the doors open and the refrigerator on, climbed a whopping ten degrees early this morning!  

Yay,  “mo better” humidity for storms!  This will mean lower cloud bases today, and that in turn means that the rain that falls out of the thunderheads with their anvils (aka, “Cumulonimbus capillatus incus” clouds, if you want to impress your friends) will reach the ground in torrents; the  rainshafts will be opaque under those clouds.   This will be quite unlike yesterday, where rain fell,  grudgingly it seemed,  from the isolated, high-based, and rather shallow Cumulonimbus clouds seen around Catalina.   This is the first day that, to focus on MYSELF for a second, I….have waited for all year!  I am not one of those little babies that can’t take a little heat and humidity of the Arizona summer and have to head off to his/her mountain palaces or shacks, as the case may be.

Now, of course, if you have any photographic documentation inclinations, you’ll definitely want to get some “before” shots of dusty cacti, dust-covered mesquite trees, your car, check the amount rocks around the little hill your house is on (I don’t think we have enough, for example) and be ready to get some “after” shots once our summer summer’s rains begin and the dead desert springs to life, one of nature’s big miracles around here.  In fact, it would be that bit better if you had a time lapse camera set up so that we could see this change take place over a period of a month or two.  Thanks in advance for doing this! I look forward to seeing your work.

Below, an example of dead desert taken during a horseback ride yesterday.    Also note in the second photo,  some large black birds in formation on the top of telephone poles, wings out.   Sometimes they extend for miles on top of telephone poles.   They do this when the relative humidity is about to go up in some kind of homage.  (OK, I made this up.)

How much rain can fall in our most intense rainshafts, the kind that you can’t see through, are virtually black, and also have just dropped down from the cloud?  (In “conversational meteorology”, when this happens, you might exclaim to dinner guests, “What happened to the view of the Tortolitas?  Just a minute ago there was only a dark cloud base over them, and now, 2 minutes later you can’t see them at all!  Man, look at that shaft of rain over there!”  A murmur develops among your guests…  They’re impressed by your interest in natural events.

Well, we have our measurements here in Arizona.   And once in a great while, something extraordinary like this “bottom drops out” situation hits a hi res gage.  Well, Floridians, you don’t have that much on us.  Our gages have indicated that a whopping  1-2 inches of rain can fall in but 15 minutes!  Unbelievable!  In those cases, its pretty much a whiteout inside the heart of that newly fallen shaft, and your roof will become the equivalent of Bridal Veil Falls, Yosemite.

Please note black dots on top of telephone poles in second photo.  They’re birds.  A close up follows, so that you can see I did not just make this up.  The clouds?  Center:  Altocumulus opacus virgae (has some stuff falling out it) with some “perlucidus” thrown in.

The End, except for the photos below.

By Art Rangno

Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa.