Various methods of estimating atmospheric radiation including the use of radiation charts and six empirical formulas are examined, using micrometeorological data collected at Davis, Calif. The Bolz method for adjusting the clear-sky estimates of atmospheric radiation from empirical formulas for cloudy, conditions is studied using observed cloud conditions and measured atmospheric radiation. This method works well for overcast low-cloud conditions. However, in high-cloud conditions with less than complete sky coverage, it is less satisfactory, perhaps due to problems in analytically representing the cloud conditions.