Download File - Mr. Volpe`s Earth Science Emporium

Moisture in the Atmosphere
Moisture in the Atmosphere
The primary source of moisture for the
Evaporation of oceans
atmosphere is the ____________.
Other sources include:
Lakes, rivers, soil, plants
___________________________________
-
Moisture in the atmosphere exists in all three
Solid, liquid and gas
states/phases. (_______________________)
Terms to Know:
Humidity
______________
is the general term used to
describe the ____________________________
Amount of water vapor in the air
Page 15
 Dew
point Temperature:
Page 15
The temperature which air must be cooled
to for condensation to occur
 Relative
Humidity:
The ratio between the actual amount of
water vapor in the air to the maximum
amount of water the air can hold



percent (%)
Expressed as a ___________
If air is holding half of its capacity- unsaturated
__________
saturated
Air cooled below the dewpoint- ________________
Page 15
Saturation
Saturation- When air holds as much water as
it can at a certain temperature
Saturation occurs when:
evaporation= condensation
Key:
Air molecule
Water molecule
evaporation
condensation
a. At 1, no _____________
evaporation
has occurred.
evaporation is proceeding faster than
b. At 2, ___________
_______________
condensation
evaporation equals the rate of
c. At 3, the rate of ___________
_____________
condensation - _____________
equilibrium
has been reached
the air is ____________
saturated
Page 15
1. _____________Temperature
As temperature increases the
rate of evaporation increases
As wind increases the rate of
Wind
2. ____________evaporation increases
As humidity increases the
Humidity
3. ______________-
rate of evaporation decreases
As surface area increases
Surface Area
4. ______________-
rate of evaporation increases
Page 15
Rate of Evaporation
Rate of Evaporation
Temperature
Surface Area
Wind
Humidity
Page 15
Rate of Evaporation
Rate of Evaporation
4. ________________
Temperature
determines the amount
of water vapor the air can hold.
a.
Water vapor
Temperature
increases
b. As air temperature ______________,
the amount of water vapor the air can hold
____________.
increases
Page 15
Purple Haze Cloud
Demonstration
1.
2.
3.
4.
What are the ingredients for a clouds?
Add the ingredients
Show the class
What do you need to form a cloud?
Wear tye dye & glasses
Page 16
As Dew point and Air
Temperature Become Closer
1.
2.
3.
_____________________________________
Relative humidity increases to 100%
Air becomes saturated
_____________________________________
_____________________________________
Clouds will form
Page 16
Process by Which
Clouds Form
“Adiabatic Cooling”
1.
2.
3.
4.
Air
rises & pressure surrounding the
________________________________________
______________________________
parcel
of air decreases
This allows air molecules to expand
_______.
cool to dew point
Expansion allows air to ________________
condensation occurs and clouds form
Then_______________
Page 16

When temperature of air parcel falls to its
_____________________________________
dew point temperature
________________

Causes water vapor to ______________
condense

Allowing a cloud to appear in the sky
Page 16
Cloud Formations and Types

Clouds


Are tiny droplets of liquid water/ice crystals
suspended in air
Conditions Needed For Cloud Formation



__________________________
Moisture in the air
__________________________
Cooling temperatures
Dust particles called Condensation nuclei
__________________________________________
__________________________________________
such as salt, pollution, dust
Dust Particles or “Condensation Nuclei”
Called Aerosols, in the atmosphere, provide a surface
for water molecules to condense on
Page 16
Precipitation and Aerosols

What natural process cleans the atmosphere
Precipitation
_____________________________________

In order for rain to fall the water droplets must
be
_____________________________________
too big to stay suspended in the air and
gravity will pull the water droplets to Earth
_____________________________________
Page 16
How is air cooled?
• Contact i.e. with a cold surface such as
over land in winter.
• Convection i.e. uplift over warm ground.
• Orographic i.e. rising over mountains.
• Frontal i.e. when a mass of warm air
meets and rises over a mass of cold air.
Cloud Types
Cirrus
__________________
Wisps/curls (ice clouds)

The shape of the
cloud shows how air
moves through it
Stratus
_________________
Spread/layered (low)


Piles/heaps
Cumulus  _____________________
(grow upwards w/flat bases)


high
Alto  Prefix meaning ___________
bearing/ snow bearing
Nimbus  Rain
_____________________
Cloud shapes
Clouds can be classified by their shape and height
Flat clouds
eg Stratus (St)
Fluffy clouds
eg Cumulus (Cu)
Wispy clouds
eg Cirrus (Ci)
Cloud heights
Clouds can also be classified by height of cloudbase
Low level (below 2000m)
eg stratus
Middle level - alto
(2,000 to 6, 000m)
eg alto-cumulus
High level - cirro (above
6,000m)
eg cirrus
Spot the cloud!
Low and flat …..
Stratus
Spot the cloud!
Middle level,
fluffy …..
Alto -Cumulus
Spot the cloud!
High level,
wispy …..
Cirrus
Spot the cloud!
Rain bearing,
storm clouds …..
Cumulo-Nimbus
CLOUD FORMATION
The size and shape of clouds depends entirely on the amount
of uplift of the air. The altitude of cloud base depends on the
altitude of the condensation level ie the altitude at which
cooling air reaches dew point temperature (saturation, or
100% relative humidity)
Here, uplift is so strong
that the cloud is very deep,
and rainfall occurs.
LIMITED
UPLIFT CAUSES
SHALLOW
CLOUDS
UPLIFT CONTINUES
CLOUD BASE at
CONDENSATION LEVEL
Below, a forest fire has caused a cloud (not just
smoke) due partly to the heat casuing convection,
but mainly to the increased number of ash
particles which increase the rate of condensation.
Cloud base is constant across a wide area, as
any of the air mass (constant in temperature
and relative humidity) reaches dew point at
the same altitude - about a 1000m?
Rising air expands,
cools, relative
humidity rises to
10% at dew point
temperature above
which
condensation of
water vapour
occurs on particles
to form clouds
WHY AIR RISES (1) - RELIEF
Cloud development stops when
air is no longer forced up.
Condensation
level
SNOWDONIA
Westerly winds blow
humid air onshore from
the Atlantic Ocean
Air sinks down on leeside of high land, contracts
due to denser air, warms up, relative humidity falls
and rainfall diminishes. This results in an area of
lower rainfall, called a rain shadow. An example is
lowland to the east of Britain, such as East Anglia.
Page 17
Page 17
Relative Humidity & Dew point
1.
2.
3.
4.
5.
6.
6 A.M.
7. 100%
6 A.M.
8. 6 A.M., DEW
4 P.M.
ON
4 P.M.
OUTDOOR
R. H. 
SURFACES
6 A.M.
9. 3 TO 4 P.M.
10. B
Page 17
Relative Humidity & Dewpoint
Can you explain this graph? Page 17
•In the cool of the morning, the air can’t hold as
much moisture. We often have dew on a summer
morning
•Once the air has warmed, the relative humidity
drops since the air can hold more moisture
Page 18
DPT & Relative Humidity
Charts
Handy Dandy Earth Science
Reference Tables Page 12
Page 18
Page 18
Page 18
The “Dry Bulb”
 Don’t let it fool you. It
is just a thermometer.
 It measures the air
temperature.
 Duh!
20°
C
Page 18
The “Wet Bulb”
 Has a little wet
booty or sock tied
to the bottom.
 Gets cool when
water evaporates.
Wet Booty
12°
C
Page 18
A Dry Day…
 A lot of moisture
will evaporate.
20°
 The wet bulb will
C
be a lot cooler than
the dry bulb.
Difference between
wet bulb & dry bulb
is 12 °C.
20°
14°
C
12°
C
8°
C
C
Page 18
A Humid Day…
 A little bit of
moisture will
20°
evaporate.
C
 The wet bulb will
not be much cooler
than the dry bulb.
Difference between
wet bulb & dry bulb
is 6 °C.
14°
C
Page 18
Page 12 of your Handy Dandy
Earth Science Reference
Tables
 Warning #1: Be sure to READ the correct chart:
DPT or RH
 Warning #2: Dew Point Temperature IS NOT
“Difference between wet bulb and dry bulb”.
 Warning #3: The wet bulb temp IS NOT the
DPT.
Dry-bulb temperature is your air temperature.
Page 18
20
°C
Page 18
14
°C
Page 18
4
°C
Subtract (the difference) between the dry
bulb and wet bulb
Page 18
Page 18
20°
C
14°
C
20-14=6
Page 18
18°
C
16°
C
18-16=2
Page 18
20°
C
Put it all together
8°
C
20-8=12
Relative Humidity = 11%
Page 18
14°
C
10°
C
14-10=4
Relative Humidity = 60%
Page 18
The Dew Point Chart works the same way
14°
C
10°
C
14-10=4
Dew Point = 6°C
Page 18
Try These
Dry Bulb
Wet Bulb
22°C
20 °C
22 °C
13 °C
20 °C
14 °C
15 °C
12 °C
9 °C
3 °C
8 °C
6 °C
17 °C
17 °C
R Humidity DPT
83%
33%
51%
70%
31%
74%
100%
19 °C
5 °C
10 °C
10 °C
-7 °C
3 °C
17 °C
Page 19
Determine Cloud Base Altitude
 Cloud Base Altitude is the minimum
height, above the Earth’s surface, at which
clouds begin to form
Must be given dry bulb temperature
 Need to find dew point temperature
 Use Cloud Base Altitude Chart
 Where the 2 lines intersect is your answer
Page 19
Lets try to
determine
the height
of the cloud
base
Ground
level
temperature
is 40°C
Dewpoint
temperature
is 20°C
What is
the cloud
base
height?
2.5 km
Page 19
Lets try to
determine
the height
of the cloud
base
Ground
level
temperature
is 30°C
Dewpoint
temperature
is 20°C
What is
the cloud
base
height?
1.3 km
Page 19
Lets try to
determine the
height of the
cloud base
Ground
level
temperature is
30°C
Dewpoint
temperature is
10°C
What is the
cloud base
height?
2.5 km
Page 19
Lets try to
determine the
height of the
cloud base
Ground
level
temperature is
16°C
Dewpoint
temperature is
0°C
What is the
cloud base
height?
2.0 km
Page 19
Lets try to
determine the
height of the
cloud base
Ground
level
temperature is
20°C
Dewpoint
temperature is
-2°C
What is the
cloud base
height?
2.7 km
Page 19
CONVECTION DUE TO UNEQUAL HEATING
1. Evaporation
2. Rising, expansion,
and cooling to dew
point temperature
3. Condensation
begins on
condensation
surface (aerosols,
dust)
4. Cloud forms
5. Drops get big
enough
precipitation
begins
Questions from Pages 20
1.
2.
3.
4.
5.
6.
1
2
2
4
3
4
7.
8.
9.
10.
2
2
2
4