GEOG 111 1nd Edition Exam 3 Study Guide Lectures 21 33 Lecture 21 October 17 Most missed from exam 2 6 The lapse rate is the rate of temperature drop with increasing altitude Which of the following situations is associated with the highest rate Clear day 16 What time of the year should a sea breeze be the strongest Spring 17 Surface winds over land blow at a 30 45 degree angle with respect to the isobars over a long distance 27 If the temperature of the air decreases the saturation vapor pressure will decrease and the vapor pressure will be unaffected 30 The 500 mb heights are greatest over the low latitudes Forced lifting I Forced lift a Orographic lifting tends to be cloudier and more wet on wind ward side of a mountain range i Air lifts on one side of a mountain reaches its saturation level clouds precipitation form air sinks down the other side of the mountain warming and drying out as it goes down b Frontal lift i Two air masses with different densities that do not mix warm air moves up and over the cold air ii Two scenarios 1 Warm air is stable as warm air is forced upward it s cooling adiabatically and will eventually cool to saturation light precipitation 2 Warm air is unstable same except when air reaches saturation convection thicker clouds heavier rain thunderstorms c Low level convergence forced lifting i Converging at low levels in the atmosphere it needs an outlet must convect upward 1 Ex Clouds from the sea breeze front d Upper level divergence forced lifting i Opposite of convergence ii If air is pulling apart from itself eventually there will be no air left in the area of divergence iii Accelerating winds exiting a trough cause air to rise 1 Forces air upward through the column Lecture 22 October 20 Clouds and Precipitation I Clouds a Cloud types i Cirrus high cold wispy ii Cirrocumulus high fine grained appearance bubble like clouds interwoven with blue sky 1 Rising motion with cloud elements sinking motion surrounding cloud elements 2 Variations in vertical and horizontal air motions would make for a bumpy plane ride iii Cirrostratus high very thin instead of streaks it is covering the whole sky in a layered fashion 1 Ring like appearance around the sun 2 Mini rainbow diffraction of light sun dogs iv Contrails high trail of cloud consisting of liquid water 1 Condensation and largely deposition 2 Water vapor comes out and instantaneously turns to ice crystals 3 The relative humidity is close to 100 v Altocumulus middle clouds warm similar to cirrocumulus just lower in the column vi Altostratus middle clouds warm thicker lower in atmosphere so block out sunlight more than cirrostratus 1 Ring around sun vii Stratus low level stratified effectively block out the sun 1 Can produce drizzle but not measurable viii Nimbostratus low thicker darker producing precipitation 1 Streaked appearance ix Stratocumulus low stratified not thick connected with a stable atmosphere air doesn t want to move vertically x Cumulus low level unstable atmosphere air is lifting daytime heating when the relative humidity is high vertical development late morning hours in Carolina summer xi Cumulonimbus largest cloud dark bottom thunderstorm II Precipitation a Requires the development of droplets snowflakes that are 100 times bigger than cloud water droplets ice crystals b Most of the time clouds don t have precipitation c Two processes for growing hydrometeors scientific term for precipitation i Bergeron grows ice crystals through multiple processes involving all three states of water 1 Requires a cold cloud where ice crystals water vapor and super cooled water coexist 2 Processes a Deposition of vapor ice crystal growth b Freezing also occurs but deposition is the dominant process c Evaporation of cloud water vapors i RH 100 d So ice crystals grow at the expense of cloud water e Rising air motions keep growing snowflake aloft until it becomes too heavy i Snowflake gets so heavy that it falls against the gradient melts and falls to Earth as rain or if the atmosphere is cold enough as snow Lecture 23 October 22 Hydrometeors and Precipitation Rates I Two processes for growing hydrometeors review a Bergeron grows ice crystals through multiple processes involving all 3 states of water often produces ice crystals that act as seeds for growing hydrometeors below in the warmer portions of clouds i Requires a cold cloud temperature 10 C where ice crystals water vapor and super cooled water coexist 1 High level clouds cirrus and cirrostratus 2 In the coldest time of the year winter the Bergeron process may occur in lower altitude clouds as well and can even create snow ii Processes 1 Deposition of vapor ice crystal growth vapor to ice a Freezing also occurs but mainly deposition 2 Removal of water around ice crystal so relative humidity drops 3 Evaporation of cloud water vapor 4 So ice crystals grow at the expense of cloud water 5 Rising air motions keep growing snowflake aloft until it becomes too heavy iii The Bergeron process provides a distinct glazed and or streaked appearance in clouds b Collision coalescence hydrometer grows as it collides with smaller droplets through the sky i It is the only precipitation formation process that operates in warm clouds ii Can supplement the Bergeron process in cold clouds e g super cooled droplets colliding iii Large cloud droplet falls through smaller cloud droplets accumulating them along the way iv Often contributes to the seeder feeder process process in which you have precipitation forming from the Bergeron seeds and Collision coalescence process warmer droplets that are feeding the seeds 1 Two scenarios a Rain droplets from melted snowflakes seeds are fed by the warm cloud water droplets b Cloud water droplets freeze on falling snowflakes in a process called riming i The snowflakes grow in size as it falls through the warmer part of the cloud II Controls on precipitation rate amount of precipitation time a Amount of water vapor condenses deposited out of atmosphere i Air temperature higher temp higher SVP and proximity to warm body of water how much water is available ii Rate of lifting 1 Convective lift can be 10 50 times faster than frontal lift b Distinguish between two precipitation types i Stratiform from nimbostratus cause sudden changes in temperature humidity and pressure of air 1 Where warm tropical air meets cool air and warm air is forced to rise 2 Less intense with over a longer period of time than convective precipitation ii Convective