GEO 211 1st EditionExam # 2 Study Guide Lectures: 11-15Lecture 11 (September 17)What is the hydrologic cycle?A model that illustrates the movement and exchange of water among the earth, atmosphere, and oceans1. Evaporation2. Transpiration3. Condensation4. EvaporationOver oceans evaporation is more than precipitationOver land precipitation is more than evaporation Over vegetated land surfaces transpiration is more than evaporationWhat 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 condensationLiquid 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 sublimationWater vapor to ice- 680 calories- Released in environment- Called heat of depositionWhat is humidity? Ways of specifying the amount of water vapor in the airWhat 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 airWhat 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 vaporTotal 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 masso 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/transpiration2. by temperature changes in the airWhat 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 groundHow 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 0.1µm. 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 sunriseo Remnants of the fog resembles stratus cloudo Doesn’t cover very extensive areaso 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 windo 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 belowDescribe 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 isvisible 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 sunseto Cumulus humilis- “fair-weather” cloudso Cumulus congestus- towering cumulus (Tcu), may produce light showersDescribe 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 range2. Banner clouds- clouds extending downwind of an isolated mountain peak3. Pileus clouds- smooth clouds in the form of a cap, resemble a