18 



EGYI'TIAX AGRICULTURE, 



AYKKAGE RAINFALL IN CENTIMETRES PER ANNUM, 



Cloudy days are usually hot and damp because there is 

 much moisture and the clouds prevent the heat from rising 

 into the atmosphere. Dew may be formed at night when 

 the damp air comes into contact with cold surfaces, as 

 the leaves of plants. In Egypt the dew is more important 

 than the rain. Dew often influences agricultural opera- 

 tions ; thus over-ripe crops are cut in the dewy mornings : 

 the norag can only work in the absence of dew : berseem 

 covered with dew may not, with safety, be grazed by 

 animals. 



In moister climates crops develop greater leaf surface, 

 the soil is more generally covered with vegetation and, 

 as a general rule, vegetables and fruits attain better 

 quality. Rain during the flowering season of fruit trees 

 and crops, prevents fertilisation of the flowers and the 

 production of fruit. 



The light and heat derived from the rays of the sun 

 are all important for the support of life. Many of the 

 smaller plants are unable to grow or exist in bright sun- 

 light. This is particularly the case with bacteria, and it 

 is thsmks to the li ( iz;ht of the sun, that animals are able to 



