EVAPORATION

1
EVAPORATION

• MOLECULES GAIN ENERGY FROM COLLISIONS
• ESCAPE FROM LIQUID TO GAS

2
EVAP II

• LEAVES LOW ENERGY BEHIND
• IS A COOLING PROCESS
• WHY YOU FEEL COOLER WHEN SWEAT EVAPORATES

3
SPECIFIC HUMIDITY

• MEASURE OF HOW MUCH WATER VAPOR IS IN THE AIR
• DEPENDS ON TEMP
• DOUBLES FOR EVERY 11C INCREASE

4
RELATIVE HUMIDITY

• RATIO OF HOW MUCH WATER VAPOR IS IN THE AIR WITH
  RESPECT TO THE MAXIMUM IT COULD HOLD
• 100 SATURATED

5
PSYCHROMETER

• USED TO MEASURE RH
• 2 THERMOMETERS DRY BULB AND WET BULB
• WILL NOT READ SAME TEMP DUE TO EVAPORATIVE COOLING

6
PSYCHROMETER II

• TEMPERATURE DIFFERENCE USED TO DETERMINE RELATIVE
  HUMIDITY
• SEE TABLE ON PAGE 501

7
DEWPOINT

• TEMPERATURE AT WHICH COOLING AIR BECOMES
  SATURATED
• DEPENDS ON SPECIFIC HUMIDITY
• SEE PAGE 503

8
AIR COOLING METHODS

• CONTACT WITH COLD SURFACE
• RADIATION
• MIXING WITH COLD AIR
• EXPANSION WHILE RISING

9
CONDENSATION

• OCCURS WHEN AIR COOLS
• OCCURS IN AIR AROUND NUCLEI TINY PARTICLES IN
  AIR

10
DEW

• VAPOR CONDENSES WHEN ITS TEMP COOLS TO THE
  DEWPOINT
• CONDENSES ON SURFACES

11
FROST

• VAPOR DEPOSITS WHEN ITS TEMP COOLS TO THE
  DEWPOINT THAT IS BELOW 0C
• DEPOSITS ONTO SURFACES

12
FOG

• TWO CAUSES
• RADIATION FOGS (OR GROUND FOG) OCCURS WHEN GROUND
  COOLS BELOW DEWPOINT

13
FOG II

• ADVECTION FOG OCCURS WHEN MOIST AIRE BLOWS OVER
  COOL SURFACE

14
CLOUDS

• HIGH FORM OF FOG
• CAN BE DROPLETS OR ICE CRYSTALS
• SHAPE DETERMINED BY AIR MOVEMENT

15
CUMULIFORM CLOUDS

• VERTICAL AIR MOVEMENT CAUSES GREAT PILES OF CLOUDS

16
STRATIFORM CLOUDS

• HORIZONTAL AIR MOVEMENT CAUSES LAYERS OF CLOUDS

17
NAMES

• THREE MAIN TYPES CUMULUS, STRATUS, AND CIRRUS

18
CIRRUS

• WISPY, FEATHERY, TUFTED
• SO HIGH THEY ARE MADE OF ICE CRYSTALS

19
STRATUS

• LOW LAYERS OF CLOUDS

20
CUMULUS

• FLUFFY, PUFFY, WHITE CLOUDS

21
ALTO

• MEDIUM CLOUDS

22
NIMBUS

• RAIN CLOUDS

23
CLOUDS
24
MORE CLOUDS
25
PRECIPITATION

• WATER VAPOR THAT CONDENSES AND FORMS CLOUDS CAN
  FALL TO EARTH AS RAIN, SLEET, SNOW, OR HAIL

26
RAINDROPS

• CLOUD DROPLETS GROW TO FORM RAIN DROPS
• SEE PAGE 512

27
FORMS OF PRECIP

• SLEET ICE PELLETS
• HAIL FORMS IN CUMULONIMBUS CLOUDS DURING
  UPDRAFTS

28
MEASURING PRECIP

• USE A RAIN GAUGE
• MELT SNOW
• 10 IN SNOW 1 IN OF RAIN

29
PRECIP LOCATIONS

• ANY PLACE AIR RISES IN LARGE AMOUNTS
• WINDWARD SIDES OF MOUNTAINS
• CONVERGING WINDS