1. Water vapour or water vapor

2. Water vapour This is found from 6.7μm channel This is in the IR region of the spectrum This wavelength radiation is absorbed by water vapour

3. What do we see? We don’t see the surface Note to me: Draw pictures

4. Atmospheric radiation The atmosphere is an object and has a temperature It will radiate IR and, in particular, at 6.7μm The more water vapour there is, the higher in the atmosphere the radiation has to start to avoid being absorbed and reaching the satellite

5. So we see Radiation from a certain level in the atmosphere This will have a certain temperature that we can find Finding the radiative temperature at 6.7μm tells us the height the radiation started from and therefore how much water vapour there is.

6. What we actually get Reality is a little different

7. Generally There is enough water vapour that the radiation comes from somewhere between 300mb and 600mb

8. The imagery

9. Water vapour and the jet-stream Polar front is marked by sharp decline in atmospheric moisture toward the pole. This marks the position of the jet stream

10. Yesterday

11. The jet stream was mighty zonal

12. WV and cyclones

13. More WV and cyclones