Radiances in water vapour channels
In the following image the threshold level is 800 hPa. The blue boxes represent layered moisture in the atmosphere. The radiation coming from below is absorbed in the lower part of a layer, and re-radiated upwards in a longer wave length from the upper part of the layer. The higher up a layer is, the lower the brightness temperature of the radiation it emits.- The solid arrows represent radiation, which comes from lower troposphere. Its brightness temperature is high.
- The dashed arrows represent radiation, which is absorbed in the middle layers. Its brightness temperature is medium.
- The triangle columns represent radiation coming from upper layers. Its brightness temperature is low.
With the help of the arrows showing the radiation going to the satellite, try to deduce which brightness temperatures and grey shades are connected to the cases A - F. First, click on one of the buttons to choose a temperature. Then, try to find the the correct letter and click on it!
| -50 °C, nearly white |
-10 °C, dark grey |
-26 °C, light grey |
-20 °C, medium grey |
+3 °C, nearly black |
-10 °C, dark grey |
| A | B | C | D | E | F |
|---|---|---|---|---|---|
| -10 °C, dark grey |
-10 °C, dark grey |
-20 °C, medium grey |
+3 °C, nearly black |
-26 °C, light grey |
-50 °C, nearly white |