In dealing with differences in upper-air relative humidity over short distances and during small time intervals, investigators have noted a tendency for low values to be reported by U.S. radiosondes, particularly those sent aloft in daytime. This paper summarizes the proceedings of a colloquium of experts who described the nature of the spurious diurnal variation and recommended the manner in which the radiosonde should be modified and in which archived data might be corrected.

The billiard sharp whom anyone catches,

His doom's extremely hard—

He's made to dwell in a dungeon cell

On a spot that's always barred.

And there he plays extravagant matches

In fitless finger stalls

On a cloth untrue, with a twisted cue

And elliptical billiard balls!

The Mikado, Act II.

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