WX 201 Exam 2 with correct Answers (Graded
A)
Analysis Chart
Depict actual data obtained at a given observation time
Forecast Chart
Computer model charts predicting future conditions of the atmosphere; surface charts and upper
level charts are created
Constant altitude charts
All locations at the same altitude above ground level (for surface analysis, pressures are typically
adjusted to MSL)
Constant pressure charts
all locations on the chart have the same pressure; contour lines of equal height of the atmospheric
column to that pressure level; typically used for elevated levels of the atmosphere such as 700 and
500 mb
How are surface analyses created?
-NOA/NWS is the primary source of data in the U.S
-Identify: lows, highs, thoughts, ridges, fronts and station model symbols
Isobaric charts
-Acquired through radiosondes, satellite, and aircraft
Upper Air Station Model
Temperature, wind, dew point, height
Standard Pressure Levels
1013mb- 0 ft
850mb- 5,000 ft
700mb- 10,000 ft
500mb- 18,000 ft
300mb- 30,000 ft
250mb- 39,000 ft
Location of jet streams
-Bands of strong wind at tropopause level
-Clear air turbulence
- lead to development and movement of cyclones
Vertical Motion
-Rising motion = air expands and cools = clouds and precipitation may form if the air is sufficiently
humid
-Sinking motion = air is compressed and warms= clearing skies
, Sources of Vertical Motion
1. Convergence / divergence
2. Topography
3. Fronts
4. Convection
5. Wave motion
6. Turbulence
Convergence / Divergence
-Convergence occurs when there is more inflow to than outflow from a region (arrows pointing
inward toward each other)
-Divergence occurs when there is more outflow from than inflow to a region (arrows away from each
other)
-Sinking motion develops when there is convergence aloft with divergence at the surface
-Rising motion develops when there is divergence aloft with surface convergence
What will cause surface low to strengthen and vice versa?
-Surface low pressure strengthens when upper level divergence exceeds surface convergence
-Surface high pressure strengthens when upper level convergence exceeds surface divergence
Buoyancy
-Less dense than surrounding fluid = positively buoyant = accelerated upward
-More dense than surrounding fluid = negatively buoyant = accelerates downward
-warmer parcel rices and colder parcels sink
Stable
generates a restoring force back to initial position
Unstable
force that accelerates the object away from initial position
Neutral Air
does not result in a force response
ELR= DALR
Stable Air
-Resists vertical motions
- Displaces air parcels restored by buoyancy back toward their initial altitude
-ELR < DALR
Unstable Air
-Vertical acceleration (upward or downward)
- vertically displaced air parcels are accelerated way from their initial altitude by positive buoyancy or
negative buoyancy
-Leads to thermals, thunderstorms, downdrafts outflow
ELR > DALR
A)
Analysis Chart
Depict actual data obtained at a given observation time
Forecast Chart
Computer model charts predicting future conditions of the atmosphere; surface charts and upper
level charts are created
Constant altitude charts
All locations at the same altitude above ground level (for surface analysis, pressures are typically
adjusted to MSL)
Constant pressure charts
all locations on the chart have the same pressure; contour lines of equal height of the atmospheric
column to that pressure level; typically used for elevated levels of the atmosphere such as 700 and
500 mb
How are surface analyses created?
-NOA/NWS is the primary source of data in the U.S
-Identify: lows, highs, thoughts, ridges, fronts and station model symbols
Isobaric charts
-Acquired through radiosondes, satellite, and aircraft
Upper Air Station Model
Temperature, wind, dew point, height
Standard Pressure Levels
1013mb- 0 ft
850mb- 5,000 ft
700mb- 10,000 ft
500mb- 18,000 ft
300mb- 30,000 ft
250mb- 39,000 ft
Location of jet streams
-Bands of strong wind at tropopause level
-Clear air turbulence
- lead to development and movement of cyclones
Vertical Motion
-Rising motion = air expands and cools = clouds and precipitation may form if the air is sufficiently
humid
-Sinking motion = air is compressed and warms= clearing skies
, Sources of Vertical Motion
1. Convergence / divergence
2. Topography
3. Fronts
4. Convection
5. Wave motion
6. Turbulence
Convergence / Divergence
-Convergence occurs when there is more inflow to than outflow from a region (arrows pointing
inward toward each other)
-Divergence occurs when there is more outflow from than inflow to a region (arrows away from each
other)
-Sinking motion develops when there is convergence aloft with divergence at the surface
-Rising motion develops when there is divergence aloft with surface convergence
What will cause surface low to strengthen and vice versa?
-Surface low pressure strengthens when upper level divergence exceeds surface convergence
-Surface high pressure strengthens when upper level convergence exceeds surface divergence
Buoyancy
-Less dense than surrounding fluid = positively buoyant = accelerated upward
-More dense than surrounding fluid = negatively buoyant = accelerates downward
-warmer parcel rices and colder parcels sink
Stable
generates a restoring force back to initial position
Unstable
force that accelerates the object away from initial position
Neutral Air
does not result in a force response
ELR= DALR
Stable Air
-Resists vertical motions
- Displaces air parcels restored by buoyancy back toward their initial altitude
-ELR < DALR
Unstable Air
-Vertical acceleration (upward or downward)
- vertically displaced air parcels are accelerated way from their initial altitude by positive buoyancy or
negative buoyancy
-Leads to thermals, thunderstorms, downdrafts outflow
ELR > DALR
