1. Introduction to Upper Air Data
Mandatory and Significant Levels
General Vertical Profiles of the Atmosphere
Upper Air Maps
TTAAs, TTBBs, PPBBs

2. Mandatory vs. Significant Levels
Mandatory levels are those that will always appear in upper air analysis gathered from radiosonde data
Significant levels are levels where there is significant data to present (usually not represented with a map but just incorporated on soundings)

3. Mandatory Levels and Heights
Surface - obviously
1000mb - varies on station elevation
925mb - varies on station elevation
850mb - ~1500m
700mb - ~3000m
500mb - ~5500m
400mb - ~7000m
300mb - ~9500m
250mb - ~11000m
200mb - ~12000m
150mb - ~14000m
100mb - ~16000m

4. Upper Air Maps This is why knowing heights is important
Dew point vs. Dew point depression
Normally temperature decreases with height until ~200mb where it becomes isothermal then increases with height in the stratosphere
Wind increasing with height until the jet stream (~250mb)
There are troughs and ridges like sfc maps
Details

5. TTAAs and TTBBs
TTAAs are mandatory level data, temperature, dew point depression, height of p level, wind speed and direction is given
TTBBs are significant level data, temperature, dew point depression, and p level is given
PPBBs are the corresponding wind data with heights of the significant levels

6. Decoding all that data
See
This link shows how to decode all this data and all the “tricks”
There are little tests on this page to help
All this data is displayed in thermodynamic charts, such as Skew T – Log P diagrams
In this class we’ll focus just on TTAA

7. 850 mb Maps How to decode station models for this level
Temp plotted upper left in Celsius
Dewpoint DEPRESSION plotted
Circle shaded if T-D is 5 or less
Height plotted in meters without first 1
Height change over 12 hours given in decameters.
Winds plotted same as surface maps

8. 850 mb Maps What is the significance of 850 mb maps?
Temperature and moisture advection
Rain/snow detection
Forecast of high and low temperature
Low level jet
Tilting of pressure systems
Height contour intervals are every 30m and isotherms are every 5 degrees

9. 700 mb Maps
Interpretation is the same as 850mb except heights are plotted without the first digit, which is a 2 or 3.
Contour intervals are every 30m and isotherms are every 5 degrees.
Used to find:
Short waves
Advections
Steering flow for storms

10. 500 mb Maps Contours are every 60 meters
Stations are plotted as on 850 & 700mb maps, but height is given without the last digit, which is a 0.
Used to find areas of vorticity advection.

11. mb Thickness plots
This plot gives the thickness of the layer of the atmosphere between 1000mb and 500mb.
Related to mean temperature of the atmosphere.
Can determine motion of organized convection (Mesoscale convective complexes)
Rain vs. Snow

12. 300/250/200 mb Maps
Contour interval is 120 m, isotachs are every 20 knots
Heights coded just like in TTAA
Used to find jet streams and jet streaks
Useful to find areas of convergence/divergence aloft.
Cyclogenesis can be enhanced
Boundary between cold and warm air

13. Combining the Upper-Air Maps
So how can using all these maps help us understand the state of the atmosphere.
Atmosphere is 3-D
Can help aid in forecasting development/decay of weather systems
Developing cyclones tilt left as you look higher in the atmosphere
Dying cyclones tend to be stacked or tilt right

14. Combining the upper air maps
Impacts for air travel?
Jet streams/streaks
Wind speed and direction aloft
Temperatures aloft
Moisture aloft
Next: Plotting and diagnosing data on a Skew-T, stability, severe wx signatures etc.