4 CLIMATE 



Aspect. This also has an important influence on climate, a. 

 northern and an eastern aspect being, as a rule, cooler and moister 

 than southerly and westerly ones; in a north verandah, for example,, 

 plants which require a cool temperature thrive much better than 

 in a verandah facing south. In a mountainous country, aspect is, 

 of course, often affected by the lay of the land, and ridges, alter- 

 nating with valleys or ravines, often cause an appreciable difference 

 in the climate of places relatively near to each other. Similarly in a 

 narrow valley, while one side, being partially shaded, may be cool 

 and damp, the other side is warm and dry ; so that plant-life would, 

 differ materially on either slope. 



Wind-breaks. The climate may be considerably improved 

 locally by the planting of shade and wind-break trees, for these- 

 not only break the force of the winds, but also tend to lessen the 

 excessive evaporation of moisture, and temper the sun's rays.. 

 Exposed and windy situations have a different climate from?, 

 sheltered places, although the soil, rainfall and aspect may be about 

 the same, Wind-breaks may be said to be as essential to many- 

 plantations as a break-water is to an open harbour 



Soil formation. Climate is also affected by the nature of 

 the soil. There is a greater radiation of heat from sandy than clay 

 soils, so that districts with sandy soils invariably have the highest 

 temperature. This largely accounts for the intense heat in parts, 

 of Egypt, Bengal, Arabia, etc., during certain seasons of the year. 



Irrigation, it is admitted, has a marked beneficial effect on 

 climate ; thus the enormous lake-like dams or reservoirs, like that 

 at Assouan in Egypt for accumulating the Nile waters, and others, 

 in India and Ceylon, must have an important influence in cooling; 

 the surrounding atmosphere. 



