48 AUTUMN AND WINTER 



gaiety and sunshine, it is not unwelcome to see the land 

 withdraw for a while into its closed horizons, and grow calm 

 in the mist and rain. No one can know England well if he 

 does not appreciate its grey weather ; and the understand- 

 ing often grows deepest when there is apparently least 

 to see. 



The connection between fog and cloud is often well 

 illustrated at nightfall on early autumn evenings, when belts 

 or layers of mist hang here and there over the fields at about 

 the height of the hedge-tops. These are simply small stratus 

 clouds, unusually close to earth. The warmed moist air near 

 the surface of the ground is chilled by the cooler upper layers 

 and condenses along the line of contact, forming these flat, 

 hanging clouds. Most day-clouds have more definite 

 rounded forms than these evening layers ; but it is not 

 uncommon to see clouds of the same flat, formless shape 

 hanging in the sky of dawn, where they are soon dissipated 

 by the warmth of the rising sun. Often on autumn evenings 

 fog forms in dense layers close to the ground, especially along 

 the beds of streams. These lower layers are caused in the 

 same way as the hanging belts, but the process is more 

 pronounced. The warmth of day draws up a great amount 

 of moisture from the stream and the wet meadows by its 

 side, which does not condense into visible mist so long as 

 the warmth is maintained, though we feel the air hot and 

 steamy. As the sun goes down, the moisture rapidly 

 condenses as the temperature descends, and colder air 

 from overlying layers and the sides of the valley mingles 

 with it. White fog lies like a blanket in the valley, and 

 does not melt, if the weather remains unchanged, until the 

 sun warms the vapour next morning, and enables it to float 

 invisibly at the higher temperature. 



Autumn is the ' season of mists ' because of the warmth 



