GEOG 111 1st Edition Lecture 18 Outline of Last Lecture I. Review from last lectureII. Water in the atmospherea. Phase changes of waterb. Effects/examplesIII. HumidityOutline of Current Lecture I. Measures of water vapor in the atmosphereII. Conclusion of temperature lectureCurrent LectureI. Measures of water in the atmospherea. Saturation- if you add any more water vapor to the atmosphere, the excess must be removed by condensation or deposition (latent phase change)i. Amount of water vapor the atmosphere can hold is due to temperatureb. Relative humidity = vapor pressure/saturation vapor pressure * 100%i. Can range from close to 0% to 100%ii. Desert environments are very far from being saturatediii. In contrast, once VP = SVP = 1 relative humidity 100% and atmosphere is saturatediv. Plays into comfort levels1. If relative humidity is low while temperature is high there is tremendousamounts of cooling through perspiration2. In contrast, in high temperatures with high relative humidity there is a very small cooling effectc. Ways to saturate the air:i. Evaporationii. Moisture advection- horizontal transport of water vapor by the wind1. Ex. Bermuda high off the coast of NC brings in clockwise winds from the Atlantic oceaniii. Decreasing the temperature of the air1. Decreasing the SVP (the atmosphere’s ability to hold water vapor)2. Radiational cooling- net radiation is negative; at night; more radiation leaving than coming ina. Inverse relationship between temperature and relative humidityi. RH is maximized in early morning and minimized late afternoonii. Evaporational cooling is greatest mid-afternoon hours (best time to work out)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.3. Virga- rain droplets that evaporate before reaching the ground because bottom layer of ground is so dry; very quickly cool down the atmospherea. Cooling always accompanies rainb. How much cooling depends on virga (which depends on relative humidity)d. Dew point temperature- the temperature to which the air must be cooled in order to reach saturationi. Serves as a readily available indicator for atmospheric water vapor contentii. Varies between 60-70siii. DPT is much higher in the summer than winter (in Eastern U.S.)1. Pacific ocean is much cooler than Atlantic so there’s not nearly as much evaporation and dew point is not nearly as highiv. Seasonal patterns of DPT1. Why is the dew point lower in the winter? Air is much colder and can’t hold as much water vapor (is dry). Also, there’s a high frequency of days in which dry continental wind is coming from the West and Northwest.2. Why is it higher in the summer? Much warmer and vegetation is more active acting as a pump through the soil (evapotranspiration through stomata). Dew point will be higher in a forest than a parking lot. Also, winds average out of the South and Southwest in the summer and are bringing in marine air.a. Trees effectively pull tons of water out of the soil and can cause an area to become more prone to droughts. v. Diurnal (day/night) patterns of DPT in the summer1. Pattern:a. Decrease 12-5 ami. Formation of dew that takes water vapor out of airb. Increase 5-9 ami. Evaporation of dewc. Decrease 10 am – 3 pmi. Convection; mixing down of more dry aird. Increase 3- 8 pmi. Thundershowers, virgaII. Conclusion of temperature lecture:a. Horizontal temperature patternsi. Specific heat- water’s is higher which requires more energy to warm up/cool downii. Surface mobility- water moves aroundiii. Water transparency- radiation can reach deeper layers (not just the surface)iv. Evaporation- not much energy left to warm waterv. Which hemisphere has the greatest seasonal temperature change? Northern Hemisphere has much more land surfaces than oceanvi. Southern Hemisphere has a marine climateb. Latitude- strongly related to annual solar insolationc. Ocean currentsi. Pacific and Atlantic oceans circulate clockwiseii. East coasts of continents have cold currents while West coasts have warm
View Full Document
Unlocking...