what causes clouds? what are their names? cumulus stratus cumulonimbus cirrus
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What causes
Clouds?What are their Names?
CumulusStratus
Cumulonimbus
Cirrus
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 VolTE stays the sameT
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)-1x (TG-dew pt) If ELR<DALR, then air is stable If ELR>DALR, then air is unstable, rising air will gain buoyancy
Altitude
(km)
DALR ~ 100C/km
ELR ~ 6.50/km
ΔDew Pt. ~ 20/km
T(0C)
Problem: Cumulus clouds are observed on a sunny afternoon. The temperature is 250C and the dew point is 70C. How high are the flat bottoms of the cumulus clouds?
Answer: 2.25 km or 7380 ft.
Cloud Types Lift 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
Name 2 ways that the moisture in an air sample can begin to
condense?1. Lower its temperature!
2. Add moisture!
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
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 = Dv / SDv x 100%
Or
RH = Partial Pv / SPv x 100%Partial Pv is P of only water molecules attaching to microdroplet
SPv is P of water molecules attaching at dew point
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)
-18-15-12-09-07-04-01020407101316
00051015202530354045505560
1.51.92.43.03.74.65.66.98.4
10.212.314.817.7
18212427293235384143464952
65707580859095
100105110115120125
21.025.029.635.041.048.156.265.676.287.8
101.4116.8134.2
1. T = 800F, Pv = 35 mb, RH?
RH = 100%
2. T = 700F, Pv = 10.2 mb, RH?
RH = 41%
3. TD = 280C, Pv = 4.6 mb, RH?
RH = 12%
4. RH = 50%, Pv = 14.8 mb, T?
T = 750F
5. T = 900F, RH = 30%, TD?
TD = 540F
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
Consider 2 parcels of air…Parcel 1: T=310F, Td=280FParcel 2: T=890F, Td=480F
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
What happens to rising air?
Altitude
Temperature
ELR-60C/km
DALR-100/km SPv
MALR: Latent heat released-5 to -60C/km
Td
Td
Stable atm
Unstable atm
tropopause
W. Jetstream
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