Inexpensive radiation shield for air temperature sensor

Commercial radiation shield – $65!

      As is well known, air temperature sensors need to be protected from direct solar radiation. Typically, they are placed in a louvered enclosure or in a radiation shield. The commercial shield shown in the image here costs $65! This makes collecting air temperature data at multiple sites pretty expensive! This document shows how to build an inexpensive version. It uses "microwavable potato bakers" I found at a local dollar store. Whether these are widely available or even still available, I do not know. But, you should be able to find other similar products.
      Truth to be told, this project requires some shop equipment that might not be readily available. The potato bakers are made of thin brittle plastic and they can be difficult to drill. I use Forstner bits, which are available from woodworking suppliers. These should be used in a drill press rather than a hand-held drill and they are not something that everybody is likely to have! More widely available "spade bits" will probably not work because they will almost certainly catch on the plastic and crack it. You could try drilling a series of small round holes around a circle and carefully cut away the plastic to make the larger ventilation openings.
      The rest of the hardware can be found at your local home improvement store. The PVC pipe can be cut with a handsaw or fine-toothed hack saw (which you will need in any case to cut the threaded rod), but I cut mine with a fine-toothed table saw blade to make sure the cuts were square.
      The temperature sensor should be mounted perpendicular to one of the pieces of PVC pipe, secured with a cable tie as shown. You could also use thin duct tape or even string. What is important is that the sensor be exposed to the air without touching the shield plate above or below.
      Assemble the unit by running the threaded pipe through the 1/4" holes in the center of each shield. Run the sensor cable through the small ventilation holes.
      As shown, the aluminum mounting bracket is straight on the mounting end. Depending on how the shield is mounted, bend it appropriately.
      How long will this shield last? Presumably not as long as the commercial version. But, that's not really too important. If it breaks or becomes significantly discolored, just replace the shield plates or build a new one. The total cost of this shield should be less than $10, so you can build at least 6 for the cost of one commercial unit even if you don't re-use the hardware!

Radiation shield components.

Radiation shield assembled.