Ripe (precipitation)
With frost is called ice deposits extending through Resublimation of water vapor to ice near the earth form and raised objects.
Frost is a crystalline , almost snow-like coating and forms on heat-radiating surfaces with low heat conduction as soon as the dew point on these surfaces is below the freezing point of the water. One differentiates between hoop, which is attributable to a cooling of the earth's surface, the radiation ripe , and frost, which is based on a horizontal air movement, the advection ripe . Radiation ripe therefore appears as a uniform coating, especially near the ground, while advection ripe forms in the form of delicate crystals on objects at high humidity, in the opposite direction from which the wind is coming.
Advection can only take place in connection with wind. This is also the main difference to the radiation ripeness. Mild and humid air is cooled on the cold surfaces, causing water vapor to condense into water and ultimately freeze off.
Frost also occurs inside snowpacks. On the one hand, this can happen through the transformation of snow crystals (evaporation in warmer, resublimation in colder snow layers); one then speaks of deep hoar or floating snow . On the other hand, layers of surface frost can be covered by new snowfalls. In both cases, such frost layers to an unstable snowpack and thus increased risk can range from slab cause avalanches.
Frost also occurs as precipitation when there is frost in the air , when the moist air freezes at a height of 2 m. However, frost should not be confused with frozen dew , hoar frost , frost or clear ice .
In contrast to the natural formation of frost in nature, technical frost also arises when air is cooled to a temperature of −2 ° C and this is strongly swirled. Well-known ripening processes in technology are:
- Frost formation on aircraft
- Snow cannons
- Zureifung an air / water heat pump or the evaporator of a refrigeration system
Web links
- Detailed article on frost formation ( memento from January 6, 2013 in the web archive archive.today )
Individual evidence
- ↑ Wetterlexikon wetter.tv ( Memento of the original from February 14, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Werner Munter : 3 × 3 avalanches. Decide in critical situations . 2nd Edition. Pohl & Schellhammer, Garmisch-Partenkirchen 1999, ISBN 3-00-002060-8 .
