Humidity

Question 1

What are clouds made out of? Can we see water vapor?

Answer 1

liquid water droplets
no, we can’t SEE water vapor

Question 2

What is relative humidity?

Answer 2

• from 0 - 100%, like in a weather report
• water vapor content/water vapor capacity

Question 3

What does 100% relative humidity mean?

Answer 3

saturation, where dew occurs

Question 4

warmer air = ?
cooler air = ?

Answer 4

warmer air means a greater maximum water vapor is possible
cooler air means a smaller maximum water vapor is possible

Question 5

adiabatic

Answer 5

a change in temperature due only to a change a pressure

Question 6

adiabatic processes

Answer 6

1) cooling by expansion: an air parcel cools internally as it expands under lower air pressure
2) heating by compression: an air parcel heats internally as it is compressed by higher air pressure

Question 7

How can we calculate how much the air cools?

Answer 7

We use the dry adiabatic rate (DAR) and moist adiabatic rate (MAR)

IMPORTANT: rising air always cools, but as it becomes saturated, the cooling rate slows

Question 8

DAR vs. MAR

Answer 8

DAR: unsaturated air, 10 degrees C/1000m
MAR: saturated air, less than 10 degrees C/1000m

Question 9

moisture droplets

Answer 9

what falls during rain, smaller than a water drop

Question 10

cloud-condensation nuclei

Answer 10

tiny particles at the center of moisture droplets, the moisture connects and forms around these particles
ex: dust, pollen, smoke, sea salt, blades of grass