Growers use giant fans to prevent grapes from freezing when the effective sky temperature is low. The grape, which may be viewed as a thin skin of negligible thermal resistance enclosing a volume of sugar water, is exposed to ambient air and is irradiated from the sky above and ground below. Assume the grape to be an isothermal sphere of 15-mm diameter, and assume uniform blackbody irradiation over its top and bottom hemispheres due to emission from the sky and the earth, respectively.

(c) With all conditions remaining the same, except that the fans are now operating with V = 1 m/s, will the grapes freeze?

Transcribed Image Text:

Sky, T Air V, T. -Grape Earth, T. 11