Aspect

This is the direction in which a slope faces, particularly with reference to sunshine.   In some areas like the Alps of Europe the South-facing slopes are warmer than the North-facing slopes.  
This is because the sun's rays strike the South-facing slopes at a steeper angle.  The slopes are exposed to direct sun rays which they intercept obliquely.  The North- facing slopes are sheltered from the direct sun rays, hence they are colder than the South-facing slopes.
In Europe,  the warm South-facing slopes are suitable for settlement and agriculture (e.g. vine cultivation) while the cold North-facing slopes are occupied by coniferous forests.
 Effect of aspect on climate