Clear skies at night allow maximum radiational cooling
, meaning heat absorbed during the day escapes from the Earth's surface.
Due to radiational cooling
conditions around sunrise, temperatures in Yilan and Su'ao dropped to 12.9 degrees Celsius Sunday morning.
As sun angles are low where ice fog occurs, radiational cooling
of the fog tops is a significant factor, allowing the cold layer to deepen and cool over days.
And you'll want to bundle up in blankets or a sleeping bag and a winter hat even in summer; it gets surprisingly cold under a clear, wide-open sky late at night due to radiational cooling
. The hat and wraps also serve as mosquito protection, reducing the amount of bug spray you'll need.
A sleeping bag provides further protection from the late-night radiational cooling
under a clear sky.
Part of the Kyushu region in southern Japan saw the mercury fall close to freezing point due to the radiational cooling
effects of the cold air, while the agency issued heavy snow warnings for Aomori, Akita and Iwate prefectures in northeastern Japan.
Looking at the starlit night, Pete remembered that if the sky is cloudless, radiational cooling
occurs when warm air escapes the earth.
The agency said the chilly weather was due to a phenomenon called radiational cooling
, which is the cooling of the earth's surface and adjacent air whenever the earth's surface suffers a net loss of heat due to terrestrial radiation.
Several basic cooling methods lend themselves to amplifiers or other operational electronics, including passive cooling (operating in a cold environment), radiational cooling
, using heat pipes to a cold sink, active cooling using liquid nitrogen refrigerant (or some other super-cooled liquid) and electrical junction cooling (a Peltier cooler or the like).
Nighttime fog is a major problem, occurring at any location where there's strong radiational cooling
and ground moisture.
Our nights are generally very humid, and radiational cooling
can quickly drop the temperature of exposed optical surfaces below the dew point, causing them to fog up.
Remember that it will be colder than you expect; on any night when the sky is clear, there will be what weather forecasters call "radiational cooling
." Even in summer, be prepared to break out pullovers, sweaters, hats, and even gloves.