Drizzle 1980717 222129359 2008-06-27T18:20:35Z Bobbywood 2000 3441427 /* Field Studies */ {{otheruses}} {{Articleissues | introrewrite = February 2008 | unreferenced = February 2008}} {{Weather nav}} '''Drizzle''' (also called '''mizzle''') is light [[precipitation (meteorology)|precipitation]] consisting of liquid water drops smaller than that of [[rain]], and generally smaller than 0.5 mm (0.02 in.) in diameter. Drizzle is normally produced by low [[Stratus cloud|stratiform]] [[cloud]]s and [[Stratocumulus_cloud|stratocumulus]] clouds. Precipitation rates due to drizzle are on the order of a millimeter per day or less at the ground. Owing to the small size of drizzle drops, under many circumstances drizzle largely evaporates before reaching the surface, and so may be undetected by observers on the ground. The [[METAR]] code for drizzle is '''DZ'''. == Effects == While most drizzle has only a minor immediate impact upon humans, [[Freezing_Drizzle|Freezing drizzle]] can lead to treacherous conditions. [[Freezing_Drizzle|Freezing drizzle]] occurs when supercooled drizzle drops land on a surface whose temperature is below freezing. These drops immediately freeze upon impact leading to the buildup of sheet ice on the surface of roads, and very heavy accumulations of ice on power lines, both of which have major impacts. == Occurrence == Drizzle tends to be the most frequent form of precipitation over large areas of the worlds oceans, particularly in the colder regions of the [[Subtropical|subtropics]]. These regions are dominated by shallow marine [[Stratocumulus_cloud|stratocumulus]] and trade wind [[Cumulus_cloud|cumulus]] clouds, which exist entirely within the marine [[Boundary_layer|boundary layer]]. Despite the low rates of surface accumulation, it is becoming apparent that drizzle actually exerts a major influence over the cloud structure, coverage, and radiative properties in these regions. This has motivated scientists to design more sophisticated, sensitive instruments such as high frequency [[Radar|radars]] that can detect drizzle. These studies have shown that the quantity of drizzle is strongly linked to cloud morphology and tends to be associated with updrafts within the marine [[Boundary_layer|boundary layer]]. Increased amounts of drizzle tend to be found in marine clouds that form in clean airmasses that have low concentrations of cloud droplets. This interconnection between clouds and drizzle can be explored using high resolution numerical modeling such as [[Large_eddy_simulation|large eddy simulation]]. == Influence of aerosols == It has been hypothesized that increasing the amounts of [[Particulate|particulates]] in the atmosphere through human activities may lead to a suppression of drizzle. According to this hypothesis, because drizzle can be an effective means of removing moisture from a cloud, its suppression could help to increase the thickness, coverage, and longevity of marine [[Stratocumulus_cloud|stratocumulus]] clouds. This would lead to increased cloud [[Albedo|albedo]] on the regional to global scale, and a cooling of the planet. Estimates using complex global [[Climate_models|climate models]] suggest that this effect may be partially masking the effects of [[Greenhouse_effect|greenhouse gas]] increases on the global surface temperature. However, it is not clear that the representation of the chemical and physical processes needed to accurately simulate the interaction between aerosols, clouds, and drizzle in our current climate models is sufficient to fully understand the global impacts of changes in particulates. == Field Studies == The forthcoming VAMOS Ocean-Cloud-Atmosphere-Land Study (VOCALS [http://www.eol.ucar.edu/projects/vocals/]) will focus upon drizzle processes and their impact upon climate. ==See also== * [[Mist]] * [[Fog]] * [[Rain]] ==References== {{reflist}} [[Category:Precipitation]] [[cs:Mrholení]] [[da:Støvregn]] [[de:Sprühregen]] [[es:Llovizna]] [[fr:Bruine]] [[it:Pioviggine]] [[lb:Fisemreen]] [[nl:Motregen]] [[ja:霧雨]] [[no:Yr]] [[nn:Yr]] [[pl:Mżawka]] [[pt:Chuvisco]] [[ru:Морось]] [[simple:Drizzle]] [[wa:Brouhene]] [[bat-smg:Dolksna]]