Estimating corn canopy extreme temperatures from shelter values

• Published in: Agricultural meteorology Vol. 8; no. 2; pp. 129 - 138
• Main Authors: Rahn, James J., Brown, D.Murray
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1971
• Subjects: weather
• ISSN: 0002-1571
• DOI: 10.1016/0002-1571(71)90102-6

Highest and lowest diurnal air and leaf temperatures in a corn canopy were compared with daily maximum and minimum temperatures in a standard thermometer shelter. Differences in temperature between canopy and shelter were related to general weather parameters. The main parameters governing the canopy-shelter differences in maximum temperature were insolation and time since the last rainfall. On bright, sunny days with low moisture, warmest leaves were 10°F (5.6°C) or more above shelter maxima, while air temperatures in the canopy were as much as 4°–6°F (2.2°–3.3°C) above shelter values. With lower insolation and/or recent rainfall, the differences decreased. Differences in minimum temperature between canopy and shelter were primarily a function of night-time radiation conditions. With atmospheric conditions favorable for radiational cooling, air minima were 2°–3°F (1.1°–1.7°C) below shelter minima, while lowest leaf temperatures were 4°–5°F (2.2°–2.8°C) below shelter values. When atmospheric moisture was high or overcast conditions existed the differences in minimum temperature between canopy and shelter were less. Tabular methods for estimating canopy-shelter temperature differences were developed, based on categories of the estimator parameters.