It is entirely erroneous to say all calefaction is from solar rays directly.
The calefaction point of water is 178°, and that of alcohol 128°.
Coal-oil-fired generators and atomic energy plants cause large amounts of waste heat which is carried away as hot water and cause thermal pollution or calefaction.
The principal producers of calefaction are power plants.
Such ecological alterations as have been observed as a result of the local calefaction of the river to date appear to be relatively inconsequential.
Synonyms
hotness, warmth, warmness, high temperature
Origin
Late Middle English: from Old French, or from late Latin calefactio(n-), from calefacere 'make warm' (see calefacient).