GEOG 203 1nd Edition Lecture 7 Outline of Last Lecture I Global atmospheric circulation models and observations II Oceanic circulation Outline of Current Lecture I Atmospheric moisture and precipitation introduction II Hydrologic cycle a brief overview III Humidity IV Condensation V Precipitation a Formation processes Current Lecture quiz answers will be on ecampus to study for test Introduction What causes dramatic precipitation patterns in small areas Understand major dry and wet areas Understanding lightening densities Tropical cyclone patterns relating to precipitation Looking at all types of precipitation rain snow sleet etc Basic ingredients for precipitation o Moisture o Atmospheric lifting Hydrologic cycle a brief overview These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Movement of water from oceans to land back to oceans o Evaporation o Transpiration o Evapotranspiration o Cloud formation o Precipitation o Runoff groundwater Humidity The gulf provides biggest source of humidity in America East texas is much more humid than west texas Saturation vapor pressure o Amount of water vapor varies partially based on temperature Relative humidity o How much humidity is present compared to how much could be present o If actual vapor pressure is 12 mb what is the relative humidity RH 100 x 12mb 24mb RH 50 o What if temperature cools to 9 degrees Celsius At this temperature saturation vapor pressure is 12 mb RH 100 x 12mb 12mb RH 100 Condensation When does condensation occur o What the temperature falls to dew point o Dew point is a temperature not expressed in MB but is a temperature related to humidity Changes from day to day and place to place as vapor pressure changes Greater the vapor pressure higher the dew point What if the air is dry that is vapor pressure is low which means dew point is below freezing o Frost forms instead of dew What if an entire layer of air is cooled to dew point o Fog or clouds form is the cool air Cumulus clouds o Form because of convection o Air cools adiabatically as it rises eventually reaching dew point o Diabatic heating adding heat to something o Adiabatic air changing temperature without addition of anything happens by expansion or compression o Cumulus Formation occurs when atmosphere is heating throughout he day and particles gradually rise because they are no longer at dew point Cirrus clouds o Whispy high up Stratus clouds o Front lot of air over large area layer of atmosphere cooled to dew point Don t need to memorize all different types of clouds Ending nimbous means rainfall occurs from that cloud Precipitation Collision coalescence model o Cloud droplets grow by collision with other droplets and coalescence of those droplets onto the growing droplets Process by which clouds can turn into rain Ice crystals model water evaporates from super cooled below 0 degrees Celsius liquid droplets and freeze onto ice crystals to form snowflakes which fall to the ground when they have grown sufficiently heavy o Mixed cloud cloud with both liquid and solid droplets o Even in warm areas snow formation can occur up high in the clouds but turn to rain before reaching the surface