GEO 211 1st Edition Exam 2 Study Guide Lectures 11 15 Lecture 11 September 17 What is the hydrologic cycle A model that illustrates the movement and exchange of water among the earth atmosphere and oceans 1 Evaporation 2 Transpiration 3 Condensation 4 Evaporation Over oceans evaporation is more than precipitation Over land precipitation is more than evaporation Over vegetated land surfaces transpiration is more than evaporation What are the many phases of water Ice to liquid 80 calories required Absorbed from environment Called latent heat of melting or fusion Liquid to water vapor 600 calories required Absorbed from the environment Called latent heat of evaporation or vaporization Water vapor to liquid 600 calories Released in environment Called latent heat of condensation Liquid to ice 80 calories Released in environment Called latent heat of freezing or fusion Ice to water vapor 680 calories Absorbed from environment Called latent heat of sublimation Water vapor to ice 680 calories Released in environment Called heat of deposition What is humidity Ways of specifying the amount of water vapor in the air What is absolute humidity The mass of water vapor in a given volume of air It represents the density of water vapor in the air Expressed as grams of water vapor per cubic meter of air g m 3 When volume increases absolute humidity decreases Not commonly used Absolute humidity mass of water vapor Volume of air What is specific humidity mixing ratio Mass of water vapor in a given mass of all the air including water vapor Specific humidity mass of water vapor Total mass of air weight over weight Mixing ratio mass of water vapor to a given mass of dry air excluding water vapor Mixing ratio mass of water vapor Mass of dry air Specific humidity and mixing ratio are both expressed as mass over mass o Grams of water vapor per kilogram of air g kg o S H and M R does not change when volume changes Fig 4 8 page 94 What is relative humidity Ratio of actual amount of water vapor in the air compared to amount required for saturation Expressed as a percentage Relative humidity actual amount content X 100 water vapor capacity OR Relative humidity actual vapor pressure X 100 saturation vapor pressure Relative humidity changes two ways 1 by evaporation transpiration 2 by temperature changes in the air What is a sling psychrometer An instrument used to measure the water vapor content of the air It consists of two thermometers dry bulb and wet bulb After whirling the instrument the dew point and relative humidity can be obtained with the aid of tables Understand how to determine relative humidity and dew point temperature on psychrometric tables handout and worksheet done in class Lecture 13 September 24 How does dew form Formed by radiation cooling on clear nights condensed liquid on objects near the ground How does frost form Formed by deposition also called hoarfrost exhibits ice crystal patterns figure 5 2 What are condensation nuclei How important are they to weather Condensation nuclei are tiny particles in the atmosphere where condensation begins Yes they are important without them relative humidities of several hundred percent would be required before condensation could begin What is haze Fine dry or wet dusk or salt particles dispersed through a portion of the atmosphere Individually these are not visible but cumulatively they will diminish visibility Dry haze particles are very small on the order of 0 1 m wet haze particles are larger Describe all types of fog How do they form and where Formed by cooling Radiation fog formed by radiational cooling on clear clam nights also called ground fog o Dissipates few hours after sunrise o Remnants of the fog resembles stratus cloud o Doesn t cover very extensive areas o Valley fog when nestled in valleys Advection fog formed when warm moist air is blown over a cooler surface and cooled to the dew point horizontal transfer by wind o Ex warm moist air over snow surfaces or cool ocean currents Upside fog forms when air rises and cools to saturation as it climbs over mountain slopes also called orographic fog o Common along eastern slopes of the rocky mountains Formed by evaporation Steam fog forms when water evaporates from water surfaces and mix with drier air above causing saturation Frontal precipitation fog forms on a warm front when raindrops evaporate as they fall into cooler air below Describe and identify 10 common types of clouds shown in your text High clouds Cirrus Ci thin wispy fibrous clouds made with ice crystals figure 5 12 sometimes appear as hooked filaments called mares tails Cirrocumulus Cc thin high clouds with small puffed masses made with ice crystals figure 5 13 appear as ripples or waves may produce mackerel sky wavelike appearance like scales of fish Cirrostratus Cs thin spread cirrus clouds with ice crystals gives sky a milky look sun moon readily shines through them figure 5 14 o Produces halos ring of light around the sun moon Middle clouds Altocumulus Ac puffy white gray masses puffs are larger than cirrocumulus figure 5 15 sometimes rolled out in parallel waves bands have water droplets not crystals Altostratus As thick spread out clouds figure 5 16 sun moon is dimly visible as a round disk referred to as watery sun Low clouds Stratus St low clouds often covers entire sky over cast figure 5 19 Stratocumulus Sc low clouds with low lumpy rounded masses figure 5 18 blue sky is visible between individual cloud elements Nimbostratus Ns dark gray rain cloud covers the entire sky over cast figure 5 17 not a lot of thunder lightning Clouds of vertical development 2 types Cumulus Cu puffy look like floating cotton often characterized by flat bases figure 5 20 burn off after sunset o Cumulus humilis fair weather clouds o Cumulus congestus towering cumulus Tcu may produce light showers Describe and identify the six unusual clouds shown in the text Where do they develop 1 Lenticular clouds lens shaped clouds form when air flows across a mountain range 2 Banner clouds clouds extending downwind of an isolated mountain peak 3 Pileus clouds smooth clouds in the form of a cap resemble a silken scarf capping the top of a developing cumulus cloud 4 Mammatus clouds clouds that look like pouches hanging from the underside of a cloud 5 Nacreous clouds soft pearly luster clouds form in the stratosphere visible at twilight called mother of pearl 6 Noctilucent clouds thin bluish white clouds seen at twilight in polar latitudes Form in the