# Fog Simulator - Tasks at 11 UTC

## Task List: Weather forecasting and warnings

Hopefully you have managed to go through the materials and design a weather image in your head. It is a lot of information to process, especially if you are not familiar with the terrain and climate of this area.

### Tasks at 11 UTC

### Question #7: Large scale effect

According to the ECMWF charts, what larger scale synoptic phenomenon sounds plausible to you?

Correct answer(s) is/are: 3)

Feedback for 1): No, the low pressure system is still in front of the European coast. There is a high pressure system over south Scandinavia which moves to the southeast during the day. Due to negative vorticity advection a subsidence of the air masses in Austria can be expected. This will be particularlyvalid for higher levels (geopotential at 300 hPa). The effects of this process can be seen for instance in the WV 6.2 (water vapour) images.

Feedback for 2): No, there is no cold front. Instead there is a high pressure system over south Scandinavia which moves to the southeast during the day. Due to negative vorticity advection a subsidence of the air masses in Austria can be expected. This will be particularly valid for higher levels (geopotential at 300 hPa). The effects of this process can be seen for instance in the WV 6.2 (water vapour) images.

Feedback for 3): Yes, this will be particularly valid for higher levels (geopotential at 300 hPa). The effects of this process can be seen for instance in the WV 6.2 (water vapour) images.

### Question #8: Verification with satellite

Can you prove your above given answer by one of the satellite images?

Correct answer(s) is/are: True

Feedback for 1): Right, if you look at the water vapour satellite images (WV 6.2) you can see clearly how darker areas are advected from the northeast. This decending drier air from higher levels.

Feedback for 2): The high pressure system over south Scandinavia moves to the southeast during the day. Due to negative vorticity advection a subsidence of the air masses in Austria can be expected. This will be particularly valid for higher levels (geopotential at 300 hPa).
If you look at the water vapour satellite images (WV 6.2) you can see clearly how darker areas are advected from the northeast. This decending drier air from higher levels.

### Question #9: Radiosounding

You have now two time steps of the radiosoundings (Vienna and Munich). Which of the statements can you confirm?

Correct answer(s) is/are: 2)

Feedback for 1): No, there is not much heating of the surface and also not all layers become distinctly drier. The upper levels however do so: while the temperature curve (right line) might not change significantly the dew point curve (left line) shifts clearly to the left, the gap between the two lines becomes larger at the 09 UTC radiosounding. That means the air gets drier which is again a sign for dry intrusion from above.

Feedback for 2): Yes, the temperature courve (right line) might not change significantly but the dew point courve (left line) shifts clearly to the left, the gap between the two lines becomes larger at the 09 UTC radiosounding. That means the air gets drier which is again a sign for dry intrusion from above.

Feedback for 3): No, there is no surface fog detected neither in Munich nor in Vienna. The temperature line (right courve) and the dew point temperature line (left courve) are too distant. Instead we can see how especially the upper levels get distinctly drier. While the temperature courve might not change significantly the dew point courve shifts clearly to the left, the gap between the two lines becomes larger at the 09 UTC radiosounding. That means the air gets drier which is again a sign for dry intrusion from above.

### Question #10: Synop observations

If you compare the synop wind measurements with the local model surface wind, what do you agree with?

Correct answer(s) is/are: 1)

Feedback for 1): Yes, that's right. Think about the effect of the wind on the fog situation/advection.

Feedback for 2): No, look at the observations again. The model and the observations agree quite well: There are generally weak winds south of the Alps and stronger winds (mainly easterly) north of the Alps. You can see the wind barbs attached to the station symbol.
Think about the effect of the wind on the fog situation/advection.

When you answer all the questions and when you are sure you are finished you can click 'Finish this part!'.

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