Atmospheric Modelling

4 chapters, with a question about each of them, and one question about the presented papers.

Open book - written?

Page is work in progress

2025

18th of January

The entire exam was open book - you could bring everything.

Theory part - open book (1.5hr)

1. Evolution of cloud droplets
   1. What determines the maximum height above cloud base a droplet will reach?
   2. Draw the evolution of a cloud droplet's radius after formation on the graph to the right (x-axis = radius, y-axis = height above cloud base)
   3. What mechanisms contribute to the growth of cloud droplets? Explain them and indicate where on the graph they are of importance.
   4. When does the droplet reach maximum height?
2. Surface pressure tendency
   1. Which equation can you use to evaluate changes in surface pressure?
   2. Is this a prognostic or a diagnostic equation? Explain.
   3. On which conservation law is the equation based?
   4. What do the different terms of the equation stand for? Explain the variables involved.
   5. What is the physical meaning of the last term? Why does this contribute to changes in surface pressure?
3. Paper: in one paper, the probabilistic outcomes of different models are evaluated based on an error metric specifically designed for this purpose.
   1. Which paper and which graph am I talking about?
   2. Explain how the considered models work.
   3. Which models underperform and why?

Exercise part - remaining time

1. Given a map with isopleths (constant geopotential height) and isotherms for the 500 hPa level.
   1. Is there warm or cold air advection at point A? Explain.
   2. Estimate the magnitude of the geostrophic wind at point A.
   3. Calculate the thermal wind at point A. You can leave the coriolis parameter as is.
2. ? forgot
3. A droplet is suspended in a cloud chamber with initial drop radius 10^-8m, vapour pressure of 23 hPa, pressure of 1000 hPa, temperature of 20 degrees Celsius, diffusion coefficient of 10^2 m^2/s and an supersaturation of 4%.
   1. If you leave the droplet for one minute, what size will it be?

2024

Different teacher!

- Draw a graph of the evolution of a raindrop through a cloud, height on the y-axis, drop radius on the x-axis

- Under what circumstances are raindrops very large? Link with equations

- When will a raindrop reach the top of a cloud? On what factors does it depend?

- Some questions about radar reflectivity and the radar reflectivity factor.