Synoptic Scale Weather

Question 1

What can the upper air analysis give us with regards to clouds?

Answer 1

You can estimate cloud layers by looking for a close temp/dewpoint spread on the upper air chart.

Question 2

What is the wavelength, duration, and examples of a Synoptic scale of motion?

Answer 2

Wavelength = 2,000 - 10,000 km
Duration = Several Days
Example = High and Lows, Wx Fronts, Hurricanes, Tropical Storms
- Usually are well-detected and forecast

Question 3

What is the wavelength, duration, and examples of a Mesoscale scale of motion?

Answer 3

Wavelength = 2 - 2,000 km
Duration = Several Hours
Example = Squall Lines, Thunderstorms, Water Spouts, Dust Devils, Land/Sea Breeze, Mountain / Valley Breeze, Chinook and Santa Ana winds
- Still causes problems in forecasting accurately because the features may be quite fast-moving

Question 4

What are extratropical cyclones?

Answer 4

Low pressure areas.

- We have to look not only at the surface position and strength of the disturbance, but also “aloft”.

Question 5

At what latitudes does a energy deficit occur?

Answer 5

45 degrees from the equator (requires the surplus on energy produced closer to the equator)

Question 6

How are air masses categorized?

Answer 6

First Letter = Tropical (T) “Warm” , Polar (P) “Cold”, Artic (A) “VERY Cold”
Second Letter = Continental (c) “Relatively dry”, Maritime (m) “Relatively moist”
Third Letter = Warm (w) “Warmer than the surface over which they are moving”, Cold (k) “Colder than the surface over which they are moving”

Question 7

What does an air mass with the third letter “w” produce?

Answer 7

• Stability
• Descending Motion
• Stratus Clouds
• Steady precipitation
• A generally “smooth” ride
• Generally poor visibility outside of clouds and precipitation
• Rime ice

Question 8

What does an air mass with the third letter “k” produce?

Answer 8

• Instability
• Rising Motion
• Cumulus Clouds
• Showery Precipitation
• Turbulence
• Generally good visibility outside of clouds and precipitation
• Clear / Mixed icing

Question 9

What are the four forces that cause wind?

Answer 9

1. Pressure gradient force
2. Coriolis force
3. Friction
4. Hydrostatic equation (vertical pressure gradient in hydrostatic balance)

Question 10

What is the Pressure Gradient Force equation?

Answer 10

PGF = (1/airdensity) x (change in pressure / distance)

Question 11

What is the Coriolis force equation?

Answer 11

CF = +/- FV
F = (2 x earth rotation rate) x (sine (latitude))
V = Wind Speed
Sine (0) = 0 “no Coriolis force at the equator”

Question 12

What is Buys-Ballot (bees-ballets) Law?

Answer 12

Stand in the northern hemisphere, wind at your back, left arm points to low causing wind.

Question 13

What is geostrophic balance?

Answer 13

When coriolis force is equal to pressure gradient force.

Question 14

What kind of material is used to combat snow on airports?

Answer 14

A potassium-based solution, since salt is corrosive. This is a very expensive alternative.

Question 15

What are the different global-scale winds from the equator to 60 degrees north called?

Answer 15

0 to 30 degrees north = NE trade winds (from NE)

30 to 60 degrees north = Midlatitude Westerlies (from SW/W)

Question 16

What is the associated altitude with each pressure level: 1,000 mb, 850 mb, 700 mb, 500 mb, and 300 mb,

Answer 16

1,013.2 = sea level
850 mb = 5,000'
700 mb = 10,000' 
500 mb = 18,000' (below f which is half atmospheric pressure)
300 mb = 30,000'

Question 17

Where does a jetstream occur, and what is the speed?

Answer 17

Normally will have speeds of 50 knots or greater
- Occurs at the “break” in the tropopause between two air masses of dissimilar temperatures, in a zone of strong latitudinal temperature gradient.

Question 18

What are isotacs?

Answer 18

Lines of constant windspeeds

Question 19

What is the seasonal variation of the jetstream, and why?

Answer 19

The jet stream is further south and stronger in the winter months because in the summer, temperature difference in center is weaker and more northern.

Question 20

Flight in the jetstream:

Answer 20

• If eastbound, pilots can get an increase of well over 100 knots by flying in the jetstream, however turbulence will preclude this.
• The greatest likelihood of turbulence is on the polar side of the jetstream (this is where the temperature gradient is greatest, and where the isotach gradient is greatest)

Question 21

What is the aviation urban legend with regards to CAT and temperature?

Answer 21

If the OAT is increasing, to exit the CAT, you must climb, the exact opposite if it is decreasing

Question 22

Aloft, a low pressure system forms where?

Answer 22

In the area of divergence, down-stream the pressure trough

Question 23

Aloft, a high pressure system exists where?

Answer 23

In the area of convergence, upstream the pressure trough, or downstream the pressure ridge

Question 24

What does an occlusion usually siginify?

Answer 24

The extratropical cyclone is mature, and may die off

Question 25

What exactly is a front?

Answer 25

The leading edge of an airmass as it moves in response to the air motion around an extratropical cyclone

Question 26

What are the balloons called that get winds/temp/pressure aloft?

Answer 26

Rawinsondes, and they are sent up every day at 12 z and 24 z