In agricultural research as well as in applied climatology as a whole, there is an increasing demand for portable meteorological field equipment capable of recording continuously more environmental factors than the conventional hygro-thermograph. The spot climate recorder described can register dry bulb, wet bulb, soil, and black globe temperatures, and wind direction and velocity on either daily or weekly charts, whichever is best for the climate survey. If desired, all these elements can be registered on one chart, but a set of two recorders has been found to be no more expensive and gives the economic advantage of making each useable separately. This is desirable for instance when a network of wind registering stations is needed (including 1 temperature each) but the complete record of moisture, radiation, etc. is sufficient at one station. The wind-recording circuits are designed for low-current drain on a 6-volt storage battery. Rather than draw on this battery to provide aspiration for the dry and wet-bulb thermometers, the wind velocity record is used to determine at which few hours the wet-bulb record may be unreliable.

Hourly wind recordings at Davis and Grimes, California, revealed that spraying operations by aircraft in summer can frequently be extended beyond the customary sunrise hours without damage by drift to adjacent crops susceptible to the spray material. The data permitted scheduling spraying according to wind types. These wind records also revealed noteworthy meteorological peculiarities. The influx of the marine air beginning in the afternoon lasts almost all night, only being replaced by the opposite flow after sunrise. This indicates that the often heard “land and sea breeze” term is not appropriate, and that rather a monsoon flow tendency prevails. It is suspected that the daily variation is primarily influenced by a daily cycle in strength and northward extension of the Arizona Low.

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