Moisture, Clouds, and Precipitation Current Weather Finish Atmospheric Circulation Humidity Clouds Precipitation For Next Class: Read Chapter 7 (pp ) Reminder: Exam 1 on September 11!

June–July ITCZ Figure 6.11

Rossby Waves Figure 6.16

Location of Polar Front and Sub-Polar Low Pressure

Blizzard of

Jet Streams Figure 6.17

Mountain-Valley Breezes Figure 6.19

Monsoonal Winds Figure 6.20

Major Ocean Currents Figure 6.21

© AMS12 Water Vapor in the Atmosphere  Humidity: any one of many ways of describing the amount of water vapor in the air Varies with the season, from one day to the next, within a single day, and from one place to another Varies with the season, from one day to the next, within a single day, and from one place to another

© AMS13 Water Vapor in the Atmosphere  Relative Humidity Compares the actual amount of water vapor in the air with the amount of water vapor that would be present if that same air were saturated Compares the actual amount of water vapor in the air with the amount of water vapor that would be present if that same air were saturated Expressed as a percentageExpressed as a percentage When air is saturated,When air is saturated, relative humidity is 100% relative humidity is 100% Varies inversely withVaries inversely with temperature temperature

Relative Humidity Figure 7.8

© AMS15 Water Vapor in the Atmosphere  Vapor Pressure Pressure produced by the gas molecules composing air depends on Pressure produced by the gas molecules composing air depends on mass of the moleculesmass of the molecules kinetic molecular activitykinetic molecular activity Air pressure at a given location can be thought of as the weight per unit area of the column of air above that location Air pressure at a given location can be thought of as the weight per unit area of the column of air above that location Water vapor’s contribution to the total air pressure is known as vapor pressure Water vapor’s contribution to the total air pressure is known as vapor pressure

© AMS16 Water Vapor in the Atmosphere  Saturated Air Raising the air temperature increases saturation vapor pressure Raising the air temperature increases saturation vapor pressure Lowering the air temperature reduces saturation vapor pressure Lowering the air temperature reduces saturation vapor pressure

Saturation Vapor Pressure Figure 7.12

Maximum Specific Humidity Figure 7.13

Humidity Patterns Figure 7.11

© AMS20 Water Vapor in the Atmosphere Precipitable Water Depth of water that would be produced if all the water vapor in a vertical column of air were condensed into liquid water Average depth decreases with latitude in response to the poleward decline in mean air temperature Varies with the seasons Not always indicative of the amount of precipitation that might fall at a particular location

Adiabatic Processes Figure 7.17

Adiabatic Cooling Figure 7.17

Adiabatic Heating Figure 7.17

Precipitation Types What are the major types of precipitation and how do they form?

Moisture Droplets Figure 7.20

Raindrop and Snowflake Formation Figure 7.21

Saturation Vapor Pressure Figure 7.12

What is Rime Ice?

Rime Ice A coating of tiny, white, ice particles caused by the rapid freezing of supercooled water droplets on impact with an object.

Rime Ice on Mt. Mitchell

Rime Ice on Beech Mountain

Heavy Rime Icing on Mt. Washington

Rime Icing on Grandfather Mountain

Snow Particle Photomicroscopy Graupel

Snow Particle Photomicroscopy

Cloud Types and Identification Figure 7.22

Atmospheric Lifting Mechanisms Figure 8.6

Orographic Precipitation Figure 8.9

Orographic Patterns Figure 8.10

Average Annual Precipitation