2007/10/01 by Julie M. Tarara, Gwen-Alyn Hoheisel, Gwen–Alyn Hoheisel · 3 citations
Earth and Planetary Sciences · Engineering · Environmental Science · #Atmospheric Ozone and Climate #Atmospheric sciences #Calibration and Measurement Techniques #Climate variability and models #Composite material #Daytime #Electromagnetic shielding #Engineering #Environmental science #Geology #Materials science #Meteorology #Nuclear engineering #Optics #Physics #Radiation #Relative humidity #Shield #Shields #Wind speed
paper · pdf · doi:10.21273/hortsci.42.6.1372
openalex publication_date 2007/10/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The importance of shielding temperature sensors from solar radiation is understood, but there is a lack of prescriptive advice for plant scientists to build inexpensive and effective shields for replicated field experiments. Using the general physical principles that govern radiation shielding, a number of low-cost, passively ventilated radiation shields built in-house was assessed for the measurement of air temperature against the same type of sensor in a meteorological “standard” Gill radiation shield. The base shield material had high albedo (≈0.9) and low emissivity (0.03). Aspirated shields were included for simultaneous measurements of temperature and relative humidity. Differences in air temperature (ΔT) between low-cost shields and the standard Gill were greatest for shields with open bottoms (up to +7.4 °C) and for those with poorly perforated sidewalls. Open-bottomed shields were prone to heating from reflected radiation. Tube-shaped shields appeared to require more than 30% sidewall perforation for convection by ambient wind (up to 4 m·s −1 ) to offset the midday radiation load of the shield. The smallest daytime ΔT were between aspirated shields and the standard Gill, averaging less than ±0.5 °C. Among passively ventilated shields, the smallest daytime ΔT consistently were produced by a shield that emulated the stacked plate design of the standard Gill for a total of U.S. 4.00 in materials and 45 min construction time. Eighty-nine percent of all daytime ΔT for the “homemade Gill” shield was 1.5 °C or less. The combination of low ambient wind speed (less than 1 m·s −1 ) and high global irradiance (greater than 600 W·m −2 ) produced the largest ΔT for all passively ventilated shields, the magnitude of which varied with shield design; stacked plate configurations were more effective shields than were tube-based configurations. Nighttime ΔT were inconsequential for all shields. Cost-effective radiation shielding can be achieved by selecting shield materials and a configuration that minimize daytime radiation loading on the shield while maximizing the potential for convective transfer of that radiation load away from the shield and the sensor it houses.