Ocn Atm 100 1st Edition Lecture 1 Outline of Last Lecture I None first lecture Outline of Current Lecture II Cloud Project III Description of cloud IV Fog identification Current Lecture Cloud Project Tweet uwaos100 2014 with a link to a picture that you took Upload picture through Twitter Use a hashtag to identify your tweet First two letters of first name First three letters of last name Example Greg Tripoli GrTri Example Tweet uwaos100 2014 Stratus clouds not quite reaching the horizon produced a vivid sunset on the west side tonight GrTri pic twitter com A05ruL3s Cloud Project Cont The Rules Tweet 12 pictures with short explanation Must be UNIQUE pictures At least 3 pictures per month Extra pictures will be counted towards extra credit max 1 per month One picture of optical phenomena per month can also be taken for extra credit Put three of your pictures into cloud scrapbook due at end of semester Academic Misconduct Caution If we find any picture sharing or fraudulent pictures You receive 15 for the project Maximum course grade of 70 Example Scrapbook Entry Date and Time Friday October 21 2011 at 3 pm Original Tweet and Picture uwaos100 2014 Cirrus clouds at Picnic Point A warm front is moving in GrTri Location and circumstance This picture was taken while walking along the path on Picnic Point in Madison Direction The camera was pointing northeast and at the horizon Description Mares tail cirrus These are thin fibrous clouds composed entirely of ice which have a distinctive hooked appearance resulting from wind shear across the falling ice particles Estimated Height or Temperature The cloud is estimated to be at approximately 30000 ft above the ground Weather Situation and Web Weather Map These clouds were formed on the northeast side of a warm front that stretched from the Minneapolis Minnesota area southeastward to Dubuque Iowa see figure xx Theory on How It Was Formed These clouds were likely formed by the rising currents of air over the top of the warm front Point Structure Total project worth 15 of overall grade 12 Tweets worth 7 5 Cloud Scrapbook 7 5 Questions Email TA Stephen Ogden sogden wisc edu Useful links Surface weather maps going back to 1996 http weather unisys com archive index php Guide to optical phenomena http www atoptics co uk no blue skies won t count for extra credit Guide to cloud types http www crh noaa gov lmk n cloud classification Back to lecture Website of the day http whirlwind aos wisc edu wxp nids nids html This is the UW AOS Department NEXRAD Radar site Look at 1 Regional composites 2 Individual radar reflectivity Doppler and Accumulated rain A Nice site because the black background contrasts nicely with radar image What is a cloud Cloud mass of air containing suspended hydrometeors water or ice that act to reduce visibility and sometimes form precipitating water Fog A cloud that is in contact with the surface Cloud Versus Haze if the suspended particles are primarily composed of a non water substance such that the air is not maintained at water or ice saturation the particles are referred to Haze rather than a cloud What causes clouds to form For a cloud to form air parcels must become saturated To do so 1 Add humidity No since vapor gas moves with the air one can not flux vapor into an air parcel except through evaporation However evaporation rates are proportional to the excess of vapor pressure over saturation vapor pressure Hence evaporation goes to zero as the relative humidity approaches 100 2 Decrease temperature to create saturation by one of the following 3 processes Radiation Conduction Expansional cooling through rising motion 3 Mix parcels of 2 differing temperatures There are 4 basic types of clouds 1 Fogs 2 Stratiform 3 Cirrus 4 Cumulus Fogs Fogs are clouds in contact with surface Different fogs are associated with different formation processes Radiation Fog Results from radiative cooling of a moist layer Radiation fog occurs when radiative processes dominate Advection Fog Results when moist air being advected over a cool surface Or when advective and dynamic processes dominate Mixing Fogs Results when mixing of parcels at two different temperatures and humidities Such as steam fog and frontal fog Upslope Fog Expansional Cooling of upscale flow
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