Summer Meteorology Knowledge Flashcards
Why is it warmer at night with clouds rather than clear skies?
Clouds absorb long wave(terrestrial) energy and re-emit it to earth. Also moisture in the air absorbs radiation.
Why does peak heating not end at 12?
Incoming radiation continues to exceed outgoing heat energy. This yields an energy surplus for two to four hours after noon depending on cloud cover. Incoming equals outgoing at max and min temps.
What models are better for predicting wind?
Canadian and NAM
What factors are looked at in order to determine severe weather?
High CAPE, helicity, shear, hodographs, lapse rate and lifted index
What model is bad for forecasting minimum temps?
MOS Guidance
What kind of sounding is evident of heavy rain? Hail?
- ) Tall, skinny profile for heavy rain
2. ) Large CAPE and lapse rates in the mid-levels
What’s a radiation inversion? Why is it weaker when there’s wind?
Radiation inversion is when the cold air is below warm air. This happens because the ground is a better absorber of energy than air. Winds mix the air causing the inversion to be weaker.
What are the lapse rates?
Dry ~10C/km
Moist ~ 6C/km
What weighs more moist or dry air?
Dry because weight of dry is 29
Weight of moist is 18
How high is the planetary boundary layer?
About 1 km
What instrument measures wind speed and direction?
Aerovane
Why does wind change speed and direction over water bodies like lakes?
Less friction over lake causes winds to increase and Coriolis force moves wind to the right
What is a chinook?
Warm, dry wind that occur when strong westerlies winds aloft flow over the Rockies. Downsloping winds dry adiabatically and warm the temp on the downwind side
What is a good example of where the subtropical highs and equatorial/subpolar lows are?
Continent of Africa. Wet where the lows are located and dry were highs are located
What airmass aids rainfall on the east coast during the summer?
Bermuda high’s southerly winds bring tropical air northward, which produces rainfall
What is the polar front?
A zone if low pressure where storms often form. It separates the warm westerlies from the cold easterlies.
What are signs to recognize a front on a surface map?
- ) Wind direction
- ) Change in dew points
- ) Temperature changes
- ) Pressure changes
- ) Cloud and precip patterns
Where are the regions of convergence and divergence in jet streaks? Strong and weak parts?
Strong convergence - left entrance Strong divergence - left exit Weak convergence - right exit Weak divergence - right entrance Most storms form in left exit region
What imagery helps show vorticity in the atmosphere well?
Water Vapor imagery
What aspects do models handle best?
Predicting temperature and jet stream patterns. Not precip
On a 700 mb chart, what %RH encloses areas of clouds?
70% and above
What aspects show chances of precip in models?
Where the 700 mb RH is above 90% and where there is high omega values.
How do we tell if surface lows will intensify?
Look for vort maxes and remember to the east of PVA we find upper level divergence, upward motion and development
How can you determine the movement of weather systems?
1) They usually move with the 500mb winds
2) Lows move toward pressure drops and highs move towards pressure rises
Veering winds can tell us?
There is warm air advection WAA moving in. Temps will increase
What does backing tell us?
Cold air advection is moving in CAA. Temps will decrease over next 24-48 hours
What do you look for in each level to forecast where severe weather will form?
300 mb- strong upper level winds downstream of trough
500mb- vort max tilted so not over surface low
700- dry conditions
850/925- low level jet that is different wind direction of above levels
Surface- classic frontal boundary with cold/warm front
What type of jet stream moves faster? Jet with meridional or zonal flow?
Meridional flow moves slower, zonal flow moves systems faster
