Short-term temperature variation in needles of Pinussilvestris L.

The temperatures of needles of 10- to 15-year-old trees of Pinussilvestris L. growing in a frost hollow in Sweden were measured with an ultraminiature thermocouple. The measurements were made in the spring of 1977, during days of variable cloudiness. During periods of full sun and very low wind speed the temperature of the needles exceeded that of the surrounding air by 12 to 15 °C.