# EARTH SCIENCE LAB Humidity and Precipitation

1. Using the Relative Humidity and Dew-Point Temperature Tables, determine the relative rumidity and dew-point temperatures for the following sling psychrometer dry and wet bulb measurements.

 1a. Dry Bulb = -14°C; Wet Bulb = -16°C : % Relative Humidity 1b. Dry Bulb = -14°C; Wet Bulb = -16°C : °C Dew-Point Temperature 1c. Dry Bulb = 20°C; Wet Bulb = 19°C : % Relative Humidity 1d. Dry Bulb = 20°C; Wet Bulb = 19°C : °C Dew-Point Temperature 1e. Dry Bulb = 40°C; Wet Bulb = 29°C : % Relative Humidity 1f. Dry Bulb = 40°C; Wet Bulb = 29°C : °C Dew-Point Temperature 1g. Dry Bulb = 28°C; Wet Bulb = 13°C : % Relative Humidity 1h. Dry Bulb = 28°C; Wet Bulb = 13°C : °C Dew-Point Temperature 1i. Dry Bulb = 10°C; Wet Bulb = 7°C : % Relative Humidity 1j. Dry Bulb = 10°C; Wet Bulb = 7°C : °C Dew-Point Temperature 1k. Dry Bulb = 30°C; Wet Bulb = 30°C : % Relative Humidity 1l. Dry Bulb = 30°C; Wet Bulb = 30°C : °C Dew-Point Temperature

2. If the air temperature is 28°C and the dew-point temperature is 1°C what is the Relative Humidity? %

3. If the air temperature is 8°C and the dew-point temperature is -9°C what is the Relative Humidity? %

4. If the air temperature is 36°C and the dew-point temperature is 33°C what is the Relative Humidity? %

5. If the air temperature is 36°C and the relative humidity is 32% what is the Dew-Point Temperature? °C

6. An air mass starts at sea level with a temperature of 12°C (plot this as a point on the Orographic Precipitation graph). The air is blown inland by an onshore wind and is forced up the flanks of a coastal mountain range. Initially, the air mass rises following the Dry Adiabatic Lapse Rate.

7. The air mass reaches the Level of Condensation at an elevation of 1000 meters (draw this as a bold, horizontal line and label it).

8. What is the air temperature of the air mass at the Level of Condensation? °C

9. What is the Relative Humidity of the air mass at the Level of Condensation? %

10. What was the dew point temperature of the air mass at sea level? °C

11. What was the Relative Humidity of the air mass at sea level? %

12. After reaching the Level of Condensation the air mass continues to rise up the flanks of the mountain range. As it rises it continues to cool but now because of the condensation it follows the Wet Adiabatic Lapse Rate of 3°C/1000 m (draw this as a line beginning at the point previously plotted).

13. The air mass reaches the summit and at a temperature of -4°C. What is the elevation of the summit? (plot this as a point on the graph) m

14. Precipitation is occurring as the air mass follows the Wet Adiabatic Lapse Rate. At the Level of Condensation and just above, in what form is this precipitation occurring?

15. Precipitation is occurring as the air mass follows the Wet Adiabatic Lapse Rate. Near the summit, in what form is this precipitation occurring?

16. After reaching the summit, the air mass descends the lee side of the mountain range. As it descends in elevation it is compressed and warmed following the Dry Adiabatic Lapse Rate (draw this as a line beginning at the point previously plotted). The air mass descends to the bottom of the mountain range to an elevation of 1000 meters.

17. As it descends what is the air temperature of the air mass at 2500, 1500 and 1000 meters?
a. At 2500 m, air temperature is equal to °C
b. At 1500 m, air temperature is equal to °C
c. At 1000 m, air temperature is equal to °C

18. What is the dew point temperature of the air mass at 1000 meters? °C

19. What is the Relative Humidity of the air mass at 1000 meters? %

20. What has happened to the Relative Humidity comparing the start and end conditions?

Give two explanation for this change.
a.
b.