Spot the Differences (14)

EQ: How does dew form on the morning ground? Title: Humidity Notes EQ: How does dew form on the morning ground? INB pg. 23

States of water *Let’s see what you know….

A. Specific Humidity Def. - Amount of water vapor in air. 1. Warm air can hold more water vapor, because its molecules are further apart have more vacancy.

B. Relative Humidity - how near the air is to its maximum capacity for holding water vapor. 1. Saturated air has a relative humidity of 100%. Let’s draw this diagram!

C. Dew point https://www.youtube.com/watch?v=xNNSugTdpqo dew- water vapor condenses on a surface (ex. Grass, shower, car window) Dew point= temp. at which saturation occurs and condensation begins.

Earth Science Lab Pg. 24: Humidity & Dew Point Lab

Pre-Lab Questions Compare specific humidity vs. relative humidity. Draw the relative humidity diagram on pg. 392 (blue txt) to help support your answer to question #1. Define dew point in your own terms. Read the “Formation of Dew and Frost” on pg. 394 Sketch a diagram on why dew forms on grass & leaves. The amount of dew decreases during the daytime. Explain why this occurs. (Hint: think about what temperature holds more water and when dew forms.)

15.5 Capacity Vapor Temperature (°C) 10 Capacity Vapor Over capacity = DEW 4.5 Capacity Vapor 0 g 4 g 8 g

D. Measuring relative humidity= psychrometer (evaporation causes cooling.)

The “Dry Bulb” Don’t let it fool you. It is just a thermometer. It measures the air temperature. Duh! 20°C

The “Wet Bulb” Has a little wet sleeve tied to the bottom. Gets cool when water evaporates. 12°C Wet Sleeve

A Dry Day… A lot of moisture will evaporate. The wet bulb will be a lot cooler than the dry bulb. 20°C 20°C 14°C 12°C 8°C Difference between wet bulb & dry bulb is 12 °C.

A Humid Day… A little bit of moisture will evaporate. The wet bulb will not be much cooler than the dry bulb. 20°C 14°C Difference between wet bulb & dry bulb is 6 °C.

Dry-bulb temperature is your air temperature. 20 °C

Subtract (the difference) between the dry bulb and wet bulb

20°C 14°C 20-14=6

18°C 16°C 18-16=2

Put it all together 20°C 8°C 20-8=12 Relative Humidity = 11%

14°C 10°C 14-10=4 Relative Humidity = 60%

Lab Instructions: Copy Data Table A & B pg. 519 (black text) into your comp. book. Draw the procedure for Part A & Part B Following instructions PRECISELY Answer 1-3 “Analysis & Conclusion” questions