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Moisture Clouds and Precipitation

Content objective:

What are we learning and why are we learning this? Content, procedures, or skills.

Vocabulary objective

Tier II: High frequency words used across content areas. Key to understanding directions & relationships, and for making inferences.

Tier III: Low frequency, domain specific terms.

Building on what we already know

Make connections to prior knowledge. This is where we build from.

From Earth Science, Tarmuck and Lutgens

Entire chapter as a PDF file:

Tarbuck Earth Sci Chap 18 Moisture, Clouds and Precipitation Publisher Power Point (google)

Moisture Clouds and Precipitation

PPT for Moisture, Clouds and Precipitation

Water can change state from solid to liquid to gas.

Changes of state heat absorbed or released Tarbuck Lutgens
relative humidity varies with temperature
sling psychrometer
air compression Cloud formation by adiabatic cooling

clouds Orographic lifting and frontal wedging Rainshadow desert airflow

Convergence and Localized convective lifting Cloud formation

Types of clouds

Click image to embiggen.

Great photos here:


types of clouds middle school poster

The Bergeron process

Some description here




One of the largest hailstones ever. 194 pounds. 8.0 inch diameter.
7/23/2010, Vivian, South Dakota.

University Corporation for Atmospheric Research

University Corporation for Atmospheric Research



Fog is a visible mist consisting of tiny water droplets or ice crystals suspended in the air at or near the Earth’s surface.

It is a type of aerosol or colloid – suspension of fine particles or liquid droplets in air or another gas.

Fog can be considered a type of low-lying cloud, usually resembling stratus.

It is heavily influenced by nearby bodies of water, topography, and wind conditions.

Fog can be local but most people don’t realize how extensive a fog bank can be. Here we see a solid blanket of fog covering all of southern New England.

Fog over all New England Newport RI Boston Hartford

US National Weather Service Boston MA, 1/4/2020

What state of matter is fog?

On physics.stackexchange we read

Fog is not a pure substance, so don’t search for its phase. It’s a mixture of water, water vapor and air.  Therefore no single PV or PT or any kind of diagram can represent its state.

But as water vapor act approximately like gas, as long as we deal with “shot”s of the system, and because this mixture is approximately uniform in composition everywhere, then we can say it is like water and water vapor system.

That’s because it really act like that in practice, pressure will be constant for some isothermal compression as this PVT surface for water suggests.

The approximated system therefor lies in “vapor and liquid” part of this PVT surface.

If you intersect a horizontal plane with this surface, In between the critical point and the triple line. The resulting curve will be where approximated fog can exist. It is way higher than the pressure of the triple line.

Liquid Vapor Solid PvT Surface for a Substance which Expands Upon Freezing

from Hyperphysics


Fog articles

Why does fog float?

Why do clouds float when they have tons of water in them?

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