Summary: In vegetation stands – especially in clear, calm weather – a temperature rise of often as much as 5 °C occurs after sunset. On the basis of model examinations the authors come to the opinion that the cause of this rise of temperature is first of all the formation of dew. This is proved by the facts that

a) the rise of température and dew formation occur simultaneously,

b) the rise of temperature and the degree of dew formation are proportionately variable.