1. What causes Clouds? What are their Names? Cumulus Stratus Cumulonimbus Cirrus

2. How does the temperature change in the troposphere? Adiabatic lapse rate = ΔT / ∆Alt. Adiabatic means TE insulated air parcel (imaginary box of air) Air Parcel P Vol TE stays the same T DALR = Dry adiabatic lapse rate = cooling rate for air parcel <dew pt. Moist ALR = cooling rate for a.p. > dew pt. (latent heat release) ELR = Environmental lapse rate = surrounding atm. lapse rate ΔDew pt. = change due to P change Lifting Condensation Level = (DALR-Δdew pt) -1 x (T G -dew pt) If ELR<DALR, then air is stable If ELR>DALR, then air is unstable, rising air will gain buoyancy Altitude (km) DALR ~ 10 0 C/km ELR ~ 6.5 0 /km ΔDew Pt. ~ 2 0 /km T( 0 C)

3. Problem: Cumulus clouds are observed on a sunny afternoon. The temperature is 25 0 C and the dew point is 7 0 C. How high are the flat bottoms of the cumulus clouds? Answer: 2.25 km or 7380 ft.

4. Cloud TypesLift Mechanism 1. Cumulus: A. Convection B. Cold fronts 2. Stratus: C. Warm fronts D. Stationary fronts 3. Cumulonimbus: E. Convergence F. Orographic lift 4. Cirrus: Match the cloud type with the probable lift mechanism(s). A C D E F A B B C D E

5. Name 2 ways that the moisture in an air sample can begin to condense? 1. Lower its temperature! 2. Add moisture!

6. Let’s recall a few terms and add one or two… Adiabatic DALR ELR Dew Pt. LR AH RH MALR = Moist ALR, the lower LR caused by latent heat release during condensation Moisture Evaporation Condensation Dew Point Undersaturation Saturation Supersaturation Lapse rate

7. What is relative humidity (RH)? Relative humidity is a percentage measure of the amount of moisture in the air compared to the total amount present at saturation for a given air temperature. RH = D v / SD v x 100% Or RH = Partial P v / SP v x 100% Partial P v is P of only water molecules attaching to microdroplet SP v is P of water molecules attaching at dew point

8. Solve these problems about air samples? Saturation Vapor Pressure at Given Temperature Temp Sat Vapor Prs (mb) Temp Sat Vapor Prs (mb) (C)(F)(C)(F) -18 -15 -12 -09 -07 -04 -01 02 04 07 10 13 16 00 05 10 15 20 25 30 35 40 45 50 55 60 1.5 1.9 2.4 3.0 3.7 4.6 5.6 6.9 8.4 10.2 12.3 14.8 17.7 18 21 24 27 29 32 35 38 41 43 46 49 52 65 70 75 80 85 90 95 100 105 110 115 120 125 21.0 25.0 29.6 35.0 41.0 48.1 56.2 65.6 76.2 87.8 101.4 116.8 134.2 1. T = 80 0 F, Pv = 35 mb, RH? RH = 100% 2. T = 70 0 F, Pv = 10.2 mb, RH? RH = 41% 3. T D = 28 0 C, Pv = 4.6 mb, RH? RH = 12% 4. RH = 50%, Pv = 14.8 mb, T? T = 75 0 F 5. T = 90 0 F, RH = 30%, T D ? T D = 54 0 F 6. Air just above the ground has a saturated vapor pressure of 4.0 mb. What phase of water will occur if the ground cools the air to the dew point? Frost

9. Consider 2 parcels of air… Parcel 1: T=31 0 F, Td=28 0 F Parcel 2: T=89 0 F, Td=48 0 F 1. Which parcel has the absolute humidity? Parcel 2 2. Which one has the highest RH? Parcel 1 3. Which one will reach its dew point first at equal cooling rates? Parcel 1 4. If both parcels reach saturation, which one has the highest potential precipitation? Parcel 2

10. What happens to rising air? Altitude Temperature ELR -6 0 C/km DALR -10 0 /km SP v MALR: Latent heat released -5 to -6 0 C/km TdTd TdTd Stable atm Unstable atm tropopause W. Jetstream