Abstract
Radiation errors of the Meteorological Office radiosonde have been obtained from calculation of the rates of absorption of radiation and of heat loss by forced convection. the effect of the heating of the radiation shield on the temperture of the air reaching the thermometer element becomes very large at high levels. The errors due to direct solar radiation and to radiation reflected and emitted from below an ascending sonde have been calculated for different solar altitudes and for heights up to 30 km.
At solar altitudes between 40Β° and 60Β° the errors amount to about 1Β°C, 2Β°5Β°C and 9Β°C at 5, 15 and 25 km respectively. Observed differences in readings from ascending and rapidly descending sondes indicated that the error at 25 km was withing about 7 per cent of the calculated value.
Lag coefficients have been derived from the heatβtransfer coefficients and the calculated value for ground level is in good agreement with laboratory measurements.
The errors of the radiosonde can account for the whole of the observed differences between day and night observtion up to 15 km. Above that height, however, the differences are appreciably greater than the errors and suggest that the daily range of temperature variation over the British Isles in spring and autumn is about 1.5Β°C at 20 km and about 3Β°C at 25 km.