Aspect
Also called: Slope aspect · Topic: Solar Radiation, Heat Balance and Temperature · NCERT: Class 11, Ch 8 "Solar Radiation, Heat Balance and Temperature"
Meaning
Aspect is the direction a slope faces. It controls how much sunshine the slope gets. In the Northern Hemisphere, south-facing slopes (called adret) face the Sun. They are sunnier, warmer and drier. North-facing slopes (called ubac) stay in shade for longer, so they are cooler and wetter. Aspect affects the snowline (the level above which snow lasts), the vegetation, farming and where people settle.
Example
In the Himalayan valleys of Himachal Pradesh and Uttarakhand, villages, terraced fields and orchards are mostly on south-facing slopes. North-facing slopes keep thicker forest and have a lower snowline.
Don't confuse with
- Air drainage: air drainage is the flow of cold air down slopes at night, and it makes valley floors colder. Aspect is about sunlight. Air drainage is about cold air settling in low places.
Related concepts
- Factors affecting insolation
- Inclination of the Earth's axis
- Summer solstice
- Angle of incidence of sun's rays