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DEFINITIONS OF WEATHER TERMS 

 (Prepared by Dr, Oscar Tenenbaum, Meteorologist in Charge^ Airport Station) 



I. STATE OF SKY 



A) Clear - Sky free or practically free from clouds (average for period less 

 than l/lO of sky covered), 



B) Cloudy or Overcast - Sky completely covered or nearly so (average for period 

 more than 9/10 of sky covered). 



Intermediate conditions betrreen clear and cloudy taken into account by use of 

 the folloTfdng terms j 



C) Scattered Clouds - Average cloudiness l/lO-^/lO sky covered, 



D) Partly Cloudy - Average cloudiness 3/IO-7/IO for period, 



E) Considerable Cloudiness or Mostly Cloudy - Average partly cloudy to overcast 

 for period. 



Modifying Terms 



Increasing cloudiness - Progressive increase in cloudiness, either in amount of 

 sky covered or in density of cloud layers. 



Decreasing cloudiness - Progressive decrease in the amount of sky covered, and/or 

 density of clouds. 



Clearing - (in general, used only after pscipitation has occurred) - Clearing sky 

 follovdng a period of mostly cloudy weather. 



Variable cloudiness - Variable amounts of cloudiness. May range from nearly 

 clear to cloudy or vice versa in a small interval of time, 



II. VJEATHER 



A) Fair - Broadly speaking, free of precipitationo Usually means not much 

 cloudiness, but can include high thin clouds which do not obscure the sun, 

 moon or stars, but only dim their intensity. In other words, the term ordin- 

 arily means sunshine most of the day, and moon or stars visible at night, 



B) Showers - Precipitation intermittent and of short duration. Characterized by 

 suddenness with -viihich precipitation starts and stops and its rapid changes 



of intensity. Often accompanied by rapid changes between dark, threatening 

 clouds and clearing conditions « 



1, General Showers (often indicated by use of word "showers" alone) means 

 that showers are expected over major portion of area, 



2, Scattered shovrers - Showers expected to affect 30-70^ of the area, 



3, Widely scattered or local showers - Showers expected to affect 30^ or 

 less of the area. 



