32 Wyo. Agricultural Experiment Station. BUL. 100 



HUMIDITY OF ATMOSPHERE. 



The humidity records give the relative degree of saturation 

 of the atmosphere. Air saturated with moisture as is usually 

 the case when it has been snowing or raining for some time, 

 contains all the moisture it will hold at that temperature and 

 the relative humidity is said to be 100 i. e. t contains 100 per 

 cent of all the moisture it will hold without precipitating more. 

 The relative humidity of the air in a fog is always 100. On the 

 other hand, air containing absolutely no moisture will have a 

 relative humidity of o. The humidity of the atmosphere may 

 range all the way from near zero to 100, depending upon con- 

 ditions. In a climate such as exists over the Laramie Plain , 

 with a rather light precipitation, we would naturally expect a 

 very dry air and we find this to be true. The average relative 

 humidity at Laramie for twenty years is 61.4. In other word>, 

 the air is only about two-thirds saturated with moisture 

 throughout the year. The atmosphere in June is only a little 

 more than half saturated with water vapor, having a relative 

 humidity of 55.2. February has the highest relative humidity, 

 69.6. 



The fact that the air is so dry has a marked effect upon 

 the evaporation. Evaporation is much in excess of the pre- 

 cipitation. 



SUNSHINE. 



The sunshine records were not complete so are not pub- 

 lished. The percentage of sunshine is very high, as is also the 

 number of clear days as compared to the cloudy and partly 

 cloudy days. 



