Study Guide Chapter 6

Study Guide Chapter 6 Describe the hydrologic cycle. List the six storage areas for water in the hydrologic cycle. Explain importance of the hydrologic cycle. 2. How old is the water you drink today? 3. What are unique properties of water? 4. What is meant by the water budget of the earth. Is the hydrosphere an open or closed system? 5. Explain the relationship between air temperature and the ability of air to store water. 6. Explain dew point and how it is determined. Explain the importance of the dew point.

Study Guide Chapter 6 continued 7. Explain relative humidity. Be able to calculate relative humidity knowing how much water vapor is stored in the air and the saturation point of the air. I will give you a specific temperature. 8. What is condensation and evaporation? What are condensation nuclei. Describe what conditions are necessary for cloud formation. 9. Describe the three basic forms of clouds. 10. Compare and contrast the formation of precipitation as rain, snow, hail, and sleet. 11. When does precipitation occur? 12. Describe adiabatic cooling. 13.Describe the rain shadow affect. 14.What conditions are necessary for precipitation.

Water-Unique Properties • Necessary for all life • 73% of Earth’s surface • Universal solvent • Total amount of water on planet remains constant

Hydrologic Cycle Closed system 4.5 billion years old

Saturation of Air • Saturation of air means that the air is holding all the water vapor that it can at a given temperature.

Water Vapor vs Air Temperature • There are limits to the amount of water vapor a parcel of air can hold • The warmer the air is the greater the amount of water vapor it can hold • What is the saturation point for 21oC? Fig. 6.4

Dew Point Temperature • If an unsaturated parcel of air is cooled, it will eventually reach a temperature where the air will become saturated. This critical temperature is known as the DEW POINT TEMPERATURE. • 30C and contains 20 g/m3 of water vapor. Saturated or unsaturated? • Cool to 21 C. Saturated or unsaturated?

Lapse Rate • When air rises its pressure decreases and so it expands and cools adiabatically

Adiabatic Lapse Rate • Dry( unsaturated) adiabatic lapse rate 100C/1000m • LCL (lifting condensation level) meters=T-Td/8*1000 Where T= temperature of parcel, Td=Dew pt. Temp. • Wet (saturated) adiabatic lapse rate= 50C/1000m • Rate of warming= 100/1000m LCL 5.11

Rain shadow Effect windward leeward Fig. 6-20a, p. 167

Percent Relative Humidity • Relative Humidity is defined as the ratio between amount of water vapor in the air at a given temperature and the maximum amount of water vapor that air can hold at that temperature. • 20 g/m3 of water vapor and that the air mass is at 30  C. What is the relative humidity? • Relative humidity= 20 /30 *100 = 67 %. This number expresses how close the air is to saturation. • Psychrometer • Desert high or low humidity? Raining relative humidity?

Sources of Atmospheric Moisture • Transpiration • Evaporation as a cooling process

Condensation • How are fogs formed? Clouds are the result of uplifting of air parcels. • What is needed to make a cloud? • Condensation nuclei, some examples? • Low pressure • Moisture

Stratus=layer Stable air Cloud Types Cumulus- heap Unstable air nimbus=raining Cirrus or wispy Strato below 6500ft.. Alto 6500-19700 ft. Cirro above 19700 ft. Nihttp://eo.ucar.edu/webweather/cloud3.html#Anchor-47857mbus = raining Fig. 6.9

Fig. 6-13, p. 161

Forms of Precipitation • Rain • Moderate temperature, fusion of water • Cooler temperatures, ice crystals • Snow • Snow occurs when a water vapor is frozen directly into a solid. The ice crystals form around nuclei and make the 6 sided symmetrical patterns of snowflakes. • Hail • Cumulonimbus clouds

Conditions for Precipitation Convectional Cyclonic/Frontal Fig. 6.18 Orographic

Precipitation • Where does the heaviest precipitation fall in the world? Why? • Figure 6.22

Study Guide Chapter 6