Studying the annual growth rings of a downed beau d’arc tree

August 9th, 2010

Beau d’arc trees have very distinct growth rings. In June one fell across the creek where we live in South-Central Texas, and I’ve finally managed to recover some rings. I waded across the creek with a very sharp saw and cut two upper canopy branches from the downed beau d’arc. Hard work at 98 degrees F. One branch goes back to 1979 and nicely covers my 20 years of sunlight measurements (including UVB and PAR–photosynthetic radiation). I plotted the width of the individual beau d’arc rings against growing season rain and temperature. Rain and cool temps yield widest rings. Plotted brightness of beau d’arc early and late wood in each ring. So far no visually obvious relationship with PAR. (Ignore the vertical lines in the photo. The squiggly line is the intensity profile across the specimen.)

See some of my sun and sky data at

This post made on 09 August 2010.

Muddy Rain Across South Texas

March 20th, 2008

On March 18, 2008, residents across South Texas were surprised to find their cars coated with a thick film of tan-colored mud from the recent rain. The National Weather Service told the San Antonio Express-News that the material was ash from fires in Mexico. The San Antonio TV meteorologists reported the material was from a massive dust storm across northern Mexico.

Who was right?

Here’s a report about this event that I sent to Bryan Lambeth at the Texas Commission on Environmental Quality and Peter Bella at AACOG
March 18, 2008

Bryan and Pete,

I swabbed material from the window using an alcohol pad and transferred some to a flat microscope slide.

The material is predominantly tan to translucent tan mineral dust ranging in size from sub micron to 20 microns.

The material includes some pollen and large black carbon particles, the latter being up to 20 microns across. A spherical nigrospora was noted. Various vegetative matter was observed.

The large black carbon suggests outdoor burning or, more likely, a brush fire origin.

Some pollen (there isn’t much) closely matches Quercus virginiana (live oak) based on my copy of E. Grant Smith’s “Sampling and Identifying Allergenic Pollens and Molds.”

Looks like I need to visit the USDA solar instruments at Texas Lutheran University that I manage for Colorado State before solar noon to remove this matter.

The TV weather people got it right.

As for the sunlight instruments that I manage for Colorado State, they were coated! The visible wavelengths were attenuated by about 10 percent before I cleaned them.