​Improved attachment decreases warming caused by solar radiation.

• Relative humidity is a function of humidity and temperature
• In daytime soundings, the humidity sensors and their contacts are warmer than the surrounding air they are measuring. This results in too low relative humidity values.
• The effect is noticeable in the upper troposphere and lower stratosphere, especially at high humidity conditions. There the radiosondes with the improved coating measure up to 5-6 %RH higher humidity values compared to those with the old coating.
• The new coating was used in the WMO Intercomparison of High Quality Radiosonde Systems in Mauritius, 2005