Q. Why does not the mist become dew?
A. Because the chill of the air is so rapid, that vapour is condensed faster than it can be deposited; and (covering the earth in a mist) prevents any further radiation of heat from the earth.
Q. When the earth can no longer radiate heat upwards, does it continue to condense the vapour of the air?
A. No; the air (in contact with the earth) becomes about equal in temperature with the surface of the earth itself; for which reason, the mist is not condensed into dew, but remains floating above the earth as a thick cloud.
Q. Why does this mist seem to rise higher and higher, and yet remain quite as dense below as before?
A. The air resting on the earth is first chilled, and chills the air resting on it; the air which touches this new layer of mist being also condensed, layer is added to layer; and the mist seems to be rising, when (in fact) it is only deepening.
Q. Why does mist and dew vanish as the sun rises?
A. Because the condensed vapour is again rarefied by the heat of the sun, and separated into invisible particles.
Q. Why is a dew-drop round?