Formation of clouds and Weather

Question 1

explain 5 reasons why clouds are important in meteorology in relation to:
Forms of weather
Precip formation
Effects on heat budget
Atmospheric processes:
Actual conditions

Answer 1

Forms of weather: their presence counts as one
Precip formation: its formed in clouds
Effects on heat budget: absorbs and reflects radiation
Atmospheric processes: provide clues to which processes are taking place
Actual conditions: can provide visual clue to amount of moisture, as well as probability for turbulence and icing

Question 2

what are the 2 main processes in the atmosphere that produce cloud:

Answer 2

Cooling

Evaporation

Question 3

what are the 2 main types of cooling

Answer 3

Adibatic cooling

Diabatic cooling

Question 4

Define the diabatic process:

Answer 4

The process in which there is an exchange or transfer of heat across the boundaries of a parcel.

Question 5

List the 3 common types of diabatic cooling

Answer 5

Radiation
Advection
Mixing

Question 6

what are the 2 examples of radiative cooling leading to the formation or modification of cloud?

Answer 6

1. Radiation cooling at the surface, through conduction, can lead to fog or stratus
2. Radiation cooling aloft may cause cloud to form or develop in the vertical

Question 7

If vertical mixing is sufficient, radiation fog may become thick enough to produce:

Answer 7

Total sky obscuration.

Question 8

The main difference between radiation fog and radiation stratus is:

Answer 8

Based on the wind speed. Light wind favors fog where moderate winds will lead to stratus

Question 9

explain how radiative cooling aloft affects stability and may lead to vertical cumuliform clouds:

Answer 9

Radiation cooling from the top of the cloud, combined with the greenhouse effect below cloud will lead to instability and vertical development clouds embedded in an SC or AC layer (ACC and TCU).

Question 10

Describe advection diabatic cooling

Answer 10

WAA is combined with conduction. warm moist air physically moves over a colder surface and loses heat to it. advection fog forms if the air is cooled to its dew point.

Question 11

Coastal stratus forms when:

Answer 11

Warm air moves across progressively colder water.

Question 12

Why will the onshore flow not produce stratus over land during the day?

Answer 12

Surface heating counteracts any inland penetration. It may form inland at night due to radiation cooling

Question 13

Explain Diabatic cooling via mixing:

Answer 13

Warm moist air may lose heat by mixing with the colder air. If the final temperature of the mixed air is below the dew point, Cloud will develop

Question 14

Clouds may form as a result of turbulent mixing. Explain:

Answer 14

When wind blows, turbulent eddies are created. These eddies result in cold air aloft warming as it is carried down, and warm air at the surface cooling as it is carried aloft. If moisture is high enough, air will become saturated at the top of the mixing layer and SC or ST will form.

Question 15

Describe the adiabatic process:

Answer 15

There is no heat exchange across the boundaries of a parcel and heating or cooling of the parcel occurs through compression or expansion of the parcel due to pressure change.

Question 16

If we lift a parcel of moist air into the atmosphere, it undergoes a decrease in

Answer 16

Density due to expansion.

Question 17

Large scale upward vertical velocity results from a combination of:

Answer 17

Low level convergence and upper level divergence

Question 18

List the 5 synoptic situations where large scale dynamic lift will often produce clouds and Wx JUVWR

Answer 18

1. Vicinity of low pressure centers and troughs
2. Regions of baroclinic development
3. in advance of Warm front and TROWALS (Max WAA)
4. ahead of Upper short wave troughs (PVA)
5. Jet stream maximums (RELE)

Question 19

state the main cause of cloud formation in the boundary layer:

Answer 19

Low level convergence generating upward vertical motion.

Question 20

The procedure for assessment of boundary layer clouds, precipitation and restrictions to visibility requires the use of:

Answer 20

a current analysis and a short range surface prognosis.

Question 21

List the 6 broad scale processes used to assess the presence of boundary layer clouds and precipitation: LUSLEC

Answer 21

1. Low level convergence
2. Upslope/Onshore flow
3. Surface winds (>15 knots)
4. Large area with moist surface conditions
5. Evaporation or precipitation
6. Cooling by advection/conduction

Question 22

The 2 factors of primary importance in regards to diurnal variations are:

Answer 22

Temperature and Humidity

Question 23

A flow of air moving over an increasingly higher ground elevation will be lifted:

Answer 23

Adiabatically.

Question 24

Explain how boundary layer clouds are lowered in precipitation

Answer 24

Precip causes an increase in moisture due to evaporation. evaporation cools the air due to latent heat storage resulting in lower temperatures. Lower temp + greater moisture = lower ceiling.

Question 25

Climatology can be helpful in describing the:

Answer 25

Persistant mesoscale effects that influence weather at a site.