Warmup
 Compare and contrast Tornado Watches with Tornado
Warnings.
 Compare the wind speed of an F5 tornado and a
Category 5 Hurricane.
 Why are hurricanes considered the most powerful
storms on Earth?
Objectives
 Today I will be able to:
 Evaluate the most important gas in the atmosphere.
 Compare and contrast saturation and relative humidity.
Key
Points
Moisture
 Water vapor is the most important gas for




understanding atmospheric processes.
Water vapor makes up 0-4 % of atmospheric gases.
Air that has reached its water vapor capacity is said to be
saturated.
Warm, saturated air contains more water vapor than
cold air.
Relative humidity is the ratio of air’s water-vapor
content to its capacity to hold water vapor at that same
temperature.
Water in the Atmosphere
 Water exists in three different forms.
 What are they?
1. SOLID Examples: Snow, ice
2. LIQUID Examples: Rain, water
3. GAS Examples: Clouds, water vapor
 How do each of these forms of water influence
weather?
Water in the Atmosphere
 When it comes to understanding atmospheric
processes, water vapor is the most important gas in the
atmosphere.
 Why do you think water vapor is so important?
Water in the Atmosphere
 Even though water vapor is important, it only makes up
from 0 – 4% of the atmospheric gases.
 When have you felt water vapor at close to 4%?
 What about 0%?
 How do you know?
 Water vapor is the HUMIDITY that you feel in the air!
Water in the Atmosphere
 What do you think the word “SATURATED” means?
 What do you think it would mean if air is Saturated?
 Air that has reached its water vapor capacity is said
to be saturated.
Water in the Atmosphere
 Warm, saturated air contains more water vapor than
cold air
 Dew point is the temperature to which air is cooled to
reach saturation.
 The point at which condensation can occur
 When have you noticed the humidity more, in the
summer or in the winter?
 That’s because warm air can hold more water vapor!
Water
in
the
Atmosphere
 Relative humidity is the ratio of air’s water-vapor




content to its capacity to hold water vapor at that
same temperature.
Relative humidity indicates how near the air is to
saturation, not the actual quantity of water vapor in
the air.
Relative Humidity varies with temperature.
Cooling air increases its relative humidity.
Warming air decreases its relative humidity.
 1% :2%
 1%:4%
 2%: 3% (cooler) 2/3
 2%: 4% (warm) 2/4
Water
in
the
Atmosphere
 Relative Humidity –
 Why does lowering the air temperature cause Relative
humidity to increase?
 Because colder air cannot hold as much water vapor!
 Why does increasing air temperature cause relative
humidity to decrease?
 Because warm air can hold more water vapor and it will
take more water vapor for it to become saturated.
Check In Questions
Answer the following questions:
1. What gas is most important for understanding
atmospheric processes?
2. Water vapor makes up what fraction of atmospheric
gases?
3. Which holds more water vapor: warm air or cool air?
4. Henderson has a humid climate. What are evidences
of humidity that you have seen?
5. How is the humidity different from the summertime
to the wintertime?
6. Why is the air in buildings so dry in the winter?
Matching- answer A, B or C for
each of the situations.
Situation
1. Water vapor is added
2. Air temperature
decreases
3. Water vapor is removed
4. Air temperature
increases
Change in Relative
Humidity:
A. Increases
B. No change
C. Decreases
Measuring Moisture
 Invent a machine that measures Relative Humidity
and Water Saturation in the air.
Draw a picture of the machine
2. Write a detailed description of how the machine
works.
3. Create instructions for how to use the machine.
1.

You will be judged based on creativity and
neatness. Be specific about how it works!
Warmup
1. Air that has reached its water-vapor capacity is
a.
2.
a.
3.
said to be:
Dry b. unstable c. stable d. saturated
The ratio of air’s water content to its capacity to
hold water at the same temperature is:
Vapor pressure b. relative humidity c. specific
humidity d. wet adiabatic rate
Water vapor makes up what fraction (%) of
atmospheric gases?
Warm up 12/2
1.
2.
3.
4.
5.
Water vapor makes up what percentage of
atmospheric gases?
What is the most important gas for understanding
atmospheric processes?
What is air called that has reached its water-vapor
capacity?
Which type of air can hold the most water-vapor?
Cold or warm?
Explain relative humidity.
Lifting Air - Objectives
 Today, I will be able to:
- Describe how air is lifted to form clouds.
- Differentiate between the types of clouds by making a
poster (if you finish all your work)
- Describe the weather associated with the different
types of clouds.
Key Points - Clouds
 When air is compressed the air temperature rises and
the air molecules move faster.
 Processes that lift air include orographic lifting, frontal
wedging and convergence.
 Examples of condensation nuclei include dust, smoke
and salt particles.
Lifting Air
 When air is compressed the air molecules move faster
and the temperature rises.
 Air compression causes changes in temperature even
though heat isn’t added or subtracted.
 When air is allowed to expand, it cools.
 When air is compressed, it heats up.
Lifting Air
 Four mechanisms that cause air to rise are:
Orographic Lifting
2. Frontal Wedging
3. Convergence
4. Localized Convective Lifting
1.
Lifting Air
1. Orographic Lifting
 Orographic lifting occurs when mountains act as barriers
to the flow of air, forcing the air to ascend.
How Air
does the relatively flat areas form clouds?
Lifting
2. Frontal Wedging
 A front is the boundary between two adjoining air
masses having contrasting characteristics.
Lifting Air
3. Convergence
 Convergence occurs when two air masses converge.
The air flows together and rises.
Lifting Air
4. Localized Convective Lifting
 Localized convective lifting occurs where unequal heating
on earth’s surface causes pockets of air to rise.
Lifting Air
Cool, expanded air
Warm, compressed
air
Clouds form
because as you
go up in
elevation, it gets
colder.
Cold air cannot
hold as much
water vapor so
it transforms
into clouds.
Lifting
Airair –expands
Creating
Clouds
 When
to form clouds,
the water vapor is
transformed to clouds by condensation.
 Generally, there must be a surface for water vapor
to condense on.
 Condensation nuclei are tiny bits of matter that
serve as surfaces on which water vapor condenses
when condensation occurs in the air.
 Examples of condensation nuclei include dust,
smoke and salt particles.
Check In Questions
1. What happens when air is
compressed?
2. Name the 4 processes that lift air.
3. Why are condensation nuclei
important?
4. Name 3 examples of condensation
nuclei.
Brochure
 Create a handout that shows the different ways air is
lifted to form clouds.
 Front flap:
 Name of the handout
 Your name and class period
 Inside flaps/back flap:
 Title each flap with the four ways air is lifted
 Draw a picture under the title on each flap
 Explain how air is lifted in your own words for each of
the flaps.
Brownie Ticket
1. Which of the following occurs when air is
compressed?
Air temperature rises
b) Air temperature cools
c) Air molecules move faster
d) Both a and c
a)
2. Name 2 examples of condensation nuclei.
3. Which of the following is NOT a process that
lifts air?
Convergence
b) Orographic lifting
c) Divergence
d) Frontal wedging
a)
Warm up – 12/3
1.
2.
3.
4.
5.
6.
What happens to air when it is compressed? (2
things)
Name 3 examples of condensation nuclei
Explain orographic lifting.
Explain frontal wedging
When are days and nights equal in length – during a
solstice or an equinox?
The heating of the lower layer of the atmosphere
from radiation absorbed by gases is called:
______________.
Clouds Objectives
 Today I will be able to:
 Classify clouds based on shape and height.
Clouds
 Now we are going to learn about the different types of
clouds and how they are classified.
 Clouds are classified based on their
height.
form (shape) and
Clouds
 Cloud types by FORM
 There are three basic forms of clouds. All other clouds
one of these three or are combinations or modifications
of them:
1. Cirrus
2. Cumulous
3. Stratus
Clouds by Form
1. Cirrus (cirrus = “curl of hair”) are clouds that are high,
white, and thin.
 Cumulus
 Stratus
Highest Clouds
 Cirrus
 Cirrostratus
 Cirrocumulus
Mid altitude clouds
 Altostratus
 Altocumulus
 Nimbostratus
Low Clouds
 Cumulus
 Stratus
 Cumulonimbus (thunderstorms, hail, tornados)
 Stratocumulus