Chapter 4:
Moisture & Atmospheric Stability

Learning Objectives

Each statement represents the primary learning objective for the corresponding section heading within this chapter.  After you complete this chapter, you should be able to:


Water vapor is an odorless, colorless gas that mixes freely with the other gases of the atmosphere. Unlike oxygen and nitrogen—the two most abundant components of the atmosphere—water can change from one state of matter to another (solid, liquid, or gas) at the temperatures and pressures experienced on Earth. Because of this unique property, water leaves the oceans as a gas and returns to the oceans as a liquid.

Chaper Outline

Water on Earth

Water's Changes of State

Humidity: Water Vapor in the Air

Relative Humidity and Dew-Point Temperature

Adiabatic Temperature Changes and Cloud Formation

Processes that Lift Air

The Critical Weathermaker: Atmospheric Stability

Stability and Daily Weather