INDIRECT MEASUREMENT 



29 



TEMPERATURE 

 SENSOR 



TEMPERATURE 

 HUMIDITY 

 SENSOR 



PRESSURE f 

 SENSOR 



BLOCKING OSCILLATOR 

 [an /AMT-6(xa-l)l 



Figure 2.4. CUnger-Slraiton radiosonde. 

 (Transmission in N units.) 



mately 2 A^ units. This then would appear to be the uhiniate precision 

 with which present conventional radiosonde sensors can yield the refrac- 

 tivity. 



The lag constants of the radiosonde sensors are also of importance. 

 Since the sonde is rising at a relatively rapid rate, it passes into regions 

 of changing refractivity before the sensors are aware of it. The lag 

 coefficient associated with the radiosonde introduces an error in the esti- 

 mation of the true gradient. Lag constants of sensors have been ana- 

 lyzed by Wexler [11] and by Bean and Button [12]. Some correction can 

 be made to the radiosonde data. Wexler (fig. 2.3) shows that the lag 

 coefficient of the lithium chloride strip is a function not only of the 

 temperature, but also of the absolute value of the relative humidity, as 

 well as of the size and direction of the gradient. 



The radiosonde samples temperature and humidity in sequence rather 

 than simultaneously. Several experimenters have devised means to cor- 

 rect this deficiency. Misme [13] decreased the cycling time in one radio- 



