Meteorology Vocabulary Review Guide
Earth Science
1. Dew point: The temperature at which water vapor begins to condense
2. Lifted condensation level: The altitude at which water vapor begins to condense because of
orographic lifting or frontal wedging.
3. Humidity: The amount of water vapor in the air.
4. Relative humidity: The ratio of humidity (how much you
have) to the capacity (amount your air can hold)
a. Equation: current humidity / capacity
5. Saturation: When an air mass is completely filled with water vapor; the air cannot hold any
more!
6. Cloud formation nuclei: Small particles in the air around which cloud droplets can form;
some examples include: dust, salt, pollution particles
7. Orographic lifting: Cloud formation process when wind encounters a mountain and the air
has no place to go but up. The warm wet air rises because of convection
8. Frontal wedging: Cloud formation process when a warm front encounters a cold front; the
warm front rises because of density differences.
9. Air stability: The ability of an air mass to resist rising; this resistance occurs because a
warm air mass loses its energy to a cool ground before it can rise. If a wet air mass can’t
rise, it won’t be able to complete any cloud formation process.
10. Condensation: State change from water vapor or gas to water or liquid; the state change
which produces clouds – water vapor in the air condenses into liquid water droplets, or
clouds; releases energy
11. Other phase changes: what to what?
a. Freezing: liquid to solid; releases
b. Melting: solid to liquid; absorbs
c. Vaporization: liquid to gas; absorbs
d. Sublimation: solid to gas; absorbs
e. Deposition: gas to solid; releases
Releases or Absorbs energy?
12. Latent heat: Energy released during a phase change from a higher to a lower state; for
example: from a gas to a liquid ~ condensation
a. This is why the atmosphere warms up when clouds are formed.
13. Laws and Relations:
a. Boyle’s: Pressure and Volume inversely related ~ one goes up and one goes down
b. Charles’: Temperature and Volume are related ~ one goes up and one goes up
14. Precipitation processes
a. Collision coalescence: individual liquid water molecules are constantly moving
inside of a cloud; they collide with one another eventually forming a large water
droplet; that water droplet is too heavy to be held up by orographic lifting, frontal
wedging, or convection any longer, and it falls out of the cloud as precipitation
b. Bergeron Process: In a multilayer cloud (such as cumulonimbus), you have large
temperature differences. In the top layers of the cloud (very cold) all of the water is
in the ice state. In the bottom layers of the cloud (relatively warmer), all of the
water is in liquid form. You will have a net movement of water molecules from the
bottom to the top because there are less ice molecules per unit volume in the top
than liquid water molecules per unit volume in the bottom. Nature likes to have the
party attendees spread out evenly. As all of the liquid water moves upward, it
freezes and a crazy amount of ice is formed - the original ice crystals grow in size,
and fall out of the cloud as they become to heavy to hold up.
15. Clouds
a. Heights
i. Strato: low
ii. Alto: middle
iii. Cirro: high
b. Types
i. Nimbus: storm cloud; anything with rain, snow, thunder, etc
ii. Stratus: dark gray blanket
iii. Cumulus: puffy
iv. Cirrus: wispy
c. Combinations
i. Cumulonimbus: multi-layer puffy storm cloud
ii. Nimbostratus: Gray blanket storm cloud
Practice synthesis question:
Synthesis: Describe in a short but thorough and detailed explanation how the 3 terms
Frontal Wedging, Relative Humidity, and Latent Heat are related in cloud formation.
The synthesis question will ask about how some cloud formation (frontal wedging or orographic
lifting) process is related to dew point or relative humidity and that cloud formation
(condensation) releases energy (latent heat). If precipitation is going to fall, it will be a nimbus
cloud.