Instruments for micro‐meteorology

Several instruments suitable for long‐term recording of temperature, humidity and wind gradients among growing crops have been constructed. Practical details are given of the use of thermistors and miniature nickel resistance thermometers as wet‐ and dry‐bulb psychrometers, and of the use of these units for direct recording of both dew point and dew‐point gradient. Modifications of the sensitive cup anemometer, appropriate circuits and details of a ‘hot‐bulb’ anemometer using a resistance thermometer, are described.