Page 216 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

7
Water and Atmospheric Moisture
concepts
key leARNiNG
After reading the chapter, you should be able to:
• Describe the heat properties of water, and identify the traits of its three phases: solid, liquid, and gas.
• Define humidity and relative humidity, and explain dew-point temperature and saturated conditions in the atmosphere.
• Define atmospheric stability, and relate it to a parcel of air that is ascending or descending.
• Illustrate three atmospheric conditions—unstable, conditionally unstable, and stable—with a simple graph that relates the environmental lapse rate (elR) to the dry adiabatic rate (DAR) and moist adiabatic rate (MAR).
• Identify the requirements for cloud formation, and explain the major cloud classes and types, including fog.
Coastal fog covers part of a redwood
forest in Humboldt Redwoods State Park, California. Coast redwoods (Sequoia sempervirens) depend on summer fog as a moisture source. As sea surface tempera- tures warm and circulation patterns shift, summer fog is declining along the California coast, with potentially negative effects
on tree health. [Michael Nichols/National Geographic.]