Maps
Thermal Wind and Advection
Convection
We're Going Streaking
Review of Vertical Motion
Trough / Ridge Structure
100
What pressure level would one would use to analyze vorticity advection?
500 mb
100
What is the definition of the thermal wind?
Change in (geostrophic) winds with height, or the vertical shear in the geostrophic wind.
100
Convective clouds are another name for these types of clouds
cumulus
100
What is a jet streak?
Area of stronger winds embedded within a jet stream
100
Divergence in the upper levels is associated with what type of vertical motion (rising or sinking)?
rising
100
What is a cut off low?
An area of reduced heights that is no longer associated with a jet stream.
200
This is the name given to contours of constant height.
isohypses
200
Warm air advection occurs when winds turn this direction with height
clockwise (veering winds)
200
Convective Available Potential Energy is a measure of this process.
instability (or buoyancy)
200
What determines the magnitude of a jet streak?
north/south temperature (or thickness) gradient
200
Positive (or cyclonic) vorticity advection is associated with what type of vertical motion?
Rising motion
200
How does warm air advection aloft impact the height field above the level of maximum warming?
Height rises are found above the area of maximum warm air advection
300
Height values on an 850 mb are approximately how high above mean sea level?
1.5 km
300
What determines the magnitude of the thermal wind?
horizontal temperature gradient
300
This environmental parameter determines the type of thunderstorm that is likely to occur.
vertical wind shear
300
Where would you expect to find divergence in this jet streak?
B & C
300
What is the primary force that causes rising motion in convective clouds?
buoyancy
300
What is a negatively tilted trough?
trough axis tilts eastward towards the south
400
Which 1000-500 mb thickness value is most commonly used to delineate the boundary between rain and snow?
5400 m (540 line)
400
What is the relationship between thermal wind and thickness?
Thermal wind vector is parallel to thickness contours.
400
Supercells are associated with 0-6 km wind shear values of at least this magnitude.
20 m/s (or 40 knots)
400
How does jet streak location relative to a trough axis impact the evolution of the trough?
Jet streak upstream rarr trough digs
Jet streak downstream rarr trough lifts
400
The plot shows 850 mb temperature advection. Would you expect rising or sinking motion over IL/IN/KY?
sinking motion
400
Would you expect this trough to dig or lift?
lift
500
How would you diagnose temperature advection on a map of only heights and temperature?
wind is parallel to height contours with cold air to the left
strong temperature advection occurs when there is a large angle between the winds (heights) and isotherms
500
How is the thermal wind vector oriented in relation to thickness contours?
parallel with colder air to the left
500
What are the 4 ingredients used in the ingredients-based approach to convective forecasting
-instability
-moisture
-trigger
-wind shear
500
Explain why a jet streak causes vertical motion
A jet streak disrupts geostrophic balance (i.e., there is a mismatch between wind speed and pressure gradient force)
As the core of the jet streak moves downstream, PGF needs to tighten and behind the jet streak it must weaken. Vertical motion alters the temperature gradient, which alters the upper level PGF.
500
Name a combination of upper level processes that would produce substantial precipitation
Jet streak divergence + Positive vorticity advection
Positive vorticity advection + Warm air advection
500
The base of this trough will move in which direction?
