Humidity
Approximately ___ to ____ % of the atmosphere is water vapor.
0-4%
Provide at least three examples of condensation nuclei
dust, smoke, bacteria, sea salt
What is a cloud?
a visible aggregate of liquid or solid water
Why does a cold fluid (liquid or gas) sink and a warm fluid rise?
Cold fluids are more dense
What is the lifting condensation level? What happens at this level and why?
Define and describe saturation
condensation and evaporation are balanced, (air is "at capacity")
As the difference between the air temperature and the dew point increases, what happens to the relative humidity?
RH decreases
What do most clouds have flat bases?
flat base indicates condensation level when air cools to dew point
What is a lapse rate? What is the environmental lapse rate? How is the environmental lapse rate measured?
change in temperature with elevation
actual, current change in temperature with elevation
measured with a radiosonde (weather balloon)
What is the general “recipe” for cloud formation? (Be able to relate it to the equation for relative humidity.)
Lift air parcel
temperature decreases
saturation vapor pressure decreases
relative humidity increases
condensation occurs
Define actual vapor pressure and saturation vapor pressure
actual vapor pressure: how much water is is currently in the air
saturation vapor pressure: how much water it takes to saturate the air (i.e. how much water the air can hold)
Dew point depends on __________________, while saturation vapor pressure depends on ________________.
options: temperature, water content
Dew point depends on water content, while saturation vapor pressure depends on temperature.
What are the three types of high clouds we learned?
cirrus, cirrostratus, cirrocumulus
What is a conditionally unstable atmosphere? How does the ELR compare to the dry and moist adiabatic lapse rate in these circumstances (larger, smaller, etc.)?
ELR is between dry and moist adiabatic lapse rates
What are the four mechanisms that result in lifted air and potential cloud formation?
surface heating/convection
orographic lifting
convergence
frontal lifting
If the temperature of an air parcel is 20C and the actual vapor pressure in 11mb, what is the relative humidity? (Use figure)
50%
Why does dew form on the ground at night? What conditions are necessary?
Ground cools off below dew point temperature
Which two key cloud types are associated with rain? Specify stormy or steady precipitation
nimbostratus - steady rain
cumulonimbus - stormy rain
Why is the dry adiabatic lapse rate greater than the moist adiabatic lapse rate?
Latent heat is released during condensation
Match the temperature profile of the lower atmosphere with the type of precipitation it produces (snow, rain, sleet, freezing rain).
(see figure)
snow, sleet, freezing rain, rain
Define and describe dew point temperature
The temperature to which an air parcel with a given water vapor content would have to be cooled for saturation to occur.
What type of fog is produced by radiational cooling of the ground and surface air to below dew point
Ground Fog/Radiation Fog/Valley Fog
Correctly identify the first five clouds in this quiz: https://scied.ucar.edu/interactive/name-cloud-game
see quiz
What causes the atmosphere to become more unstable on summer afternoons? Why are thunderstorms common in these conditions?
Ground heats up, increasing ELR
Atmosphere becomes unstable, so rising air masses produce clouds with vertical development, such as cumulonimbus
Why do hailstorms happen more often in the summer than in the winter?
Unstable atmospheric conditions are common in the summer with ground heating; this leads to the tall clouds and updrafts necessary for hail to form