Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
23 Cards in this Set
- Front
- Back
|
Explain 5 reasons why clouds are important in meteorology
|
Forms of weather:
- constituted by their presence Precipitation formation: - occurs within clouds Effects on heat budget - through absorption/reflection of radiation Atmospheric processes: - provide useful clues Actual conditions: - provides visual clues to moisture, icing, turb 302.1.1 |
|
|
State the 2 main processes in the atmosphere that produce cloud
|
- cooling via diabatic/adiabatic methods
- evaporation 302.2.1 |
|
|
Describe the diabatic process
|
Where there is an exchange or transfer of heat across the boundaries of a parcel
302.3 |
|
|
List 3 common types of diabatic cooling
|
- radiation
- advection - mixing 302.3.1 |
|
|
Explain radiation cooling at the surface in regards to diabatic cooling
|
- ground radiates energy faster than air
- conduction causes PBL to cool from below 302.3.2 |
|
|
Explain radiation fog in regards to diabatic cooling
|
- conduction may cool PBL below dew point and fog will form
- presence of lifting process will form ST instead - fog thickens as night time cooling continues - thickening may continue after sunrise due to turbulent mixing from initial daytime heating - dissipates from below as temp of low lying air increases - may break up into SF - main difference between fog and stratus primarily based on wind speed 302.3.2 |
|
|
Explain radiation cooling aloft in regards to diabatic cooling
|
- moist layer of air aloft also sends out radiation to space
- makes the moist layer unstable as tops cool faster than base - convective clouds can form as a result - can enhance vertical development of original clouds 302.3.2 |
|
|
Explain advection in regards to diabatic cooling
|
- warm moist air moves over colder surface and cools by losing heat to it
- if cooled below dew point, advection fog forms - persists as long as flow of warm moist air maintained over colder surface - onshore flow results in coastal stratus and marine fog - warm air over water moving over colder water causes coastal stratus 302.3.2 |
|
|
Explain mixing in regards to diabatic cooling
|
- warm moist air loses heat by mixing with colder air
- cold downdraft from CB can mix with warm moist air near surface to form stratus cloud in showers - clouds may form as result of turbulent mixing - if moisture content high enough, air becomes saturated at top of mixing layer and layer of ST or SC develops 302.3.2 |
|
|
Explain how the adiabatic cooling process causes the formation of clouds in the atmosphere
|
- process where there is no exchange of heat across boundaries of a parcel, and heating/cooling occurs via compression/expansion
- lifted parcel undergoes decrease in density and cooling as it expands - if cooled below dew point in the process, cloud develops within the parcel 302.4.1 |
|
|
List the 5 synoptic situations where large scale dynamic lift will often produce clouds and weather
|
- vicinity of low pressure centers/troughs
- regions of baroclinic development - warm fronts/trowals - upper short wave troughs - jet stream maximums 302.5.1 |
|
|
State the main cause of cloud formation in the boundary layer
|
Low level convergence generating upward vertical motion
302.6.1 |
|
|
List the 6 broad scale processes used to assess the presence of boundary layer clouds and precipitation
|
- low level convergence
- upslope/onshore flows - surface winds greater than 15kt - large area with moist surface conditions - evaporation of precipitation - cooling by advection/conduction 302.7.1 |
|
|
Explain the role of diurnal variations on the formation and dissipation of boundary layer clouds and weather
|
- can sometimes be sole determinant of local ceilings and visibilities
- two main factors are temperature and moisture content - temps increase during day, decrease at night - warmer temps during day allow for higher moisture content, while cooling of air at night can bring temps down to dew point 302.8.1 |
|
|
Explain the formation process associated with cumulus
|
- initially under clear skies
- from daytime heating - evaporation rate increases, which means more moisture in air - heating from below causes instability - free convection is eventually reached 302.8.2 |
|
|
Explain the evolution process associated with cumulus
|
- first, short lived CF appears
- increasing temp and moisture allow fair weather CU - bases rise due to T-Td spread growing (temp rises faster than moisture content) - once free convection reached, TCU forms - with sufficient buoyancy/kinetic energy, CB may develop 302.8.2 |
|
|
Explain the dissipation process associated with cumulus
|
- decreasing surface temp due to setting sun
- convective lift diminishes and ceases - clouds erode due to evaporation/mixing - cloud tops subside and collapse due to radiation cooling - horizontal wind may spread out or break up cloud 302.8.2 |
|
|
Explain the formation processes associated with stratocumulus/stratus
|
Daytime:
- turbulent mixing in lower layers - light wind form FG/ST, stronger winds form SC Nighttime: - stable air and clear skies - cooler air from surface lifted to mix with warmer air aloft - speed of wind has same effect as with daytime formation 302.8.2 |
|
|
Explain the dissipation processes associated with stratocumulus/stratus
|
Daytime:
- initiated by solar heating - mixing of moist air with surrounding dry air - thicker the cloud, greater amount of mixing required - stronger the capping inversion, greater the solar input required to mix Nighttime: - mixing in of dry air due to radiation cooling of cloud top creating instability - bounded by dry type inversion - low surface humidity - initially thin cloud 302.8.2 |
|
|
Explain how upslope boundary layer clouds and precipitation are formed
|
- flow of air moving over increasingly higher ground elevation is lifted adiabatically
- moisture content determines condensation 302.9.1 |
|
|
Explain how boundary layer clouds are lowered in precipitation
|
- causes increase of moisture in lower levels due to evaporation of precipitation
- evaporation process cools air - increasing dew point plus decreasing temp means dew point spread decreases - decreasing dew point spread causes cloud ceiling to lower 302.10.1 |
|
|
Explain how to determine the presence of clouds and weather using climatology
|
- provides a certain amount of instant experience
- provides quick recall to experienced individuals - describes persistent mesoscale effects 302.11.1 |
|
|
Explain how to determine the presence of clouds and weather using correlators
|
- synoptic features usually have consistent history
- timing of weather events can also be deduced - 700 hPa trough with trailing edge of synoptic cloud/precip - 500 hPa ridge with leading edge of cloud/precip - 700 hPa ridge with leading edge of cloud/precip - surface features with orientation and pattern of cloud/precip - short wave troughs/vorticity centers with trailing edges or wrap around shape - deformation zones with leading edges of cloud/precip - jet streams with edges of cloud/precip, dry surges - PVA/WAA with edges and shapes of cloud/pcpn 302.11.1 |
