Visibility
Atmospheric visibility can be described as how clear the air we look through is. Good visibility is very important to many New Zealanders and is a key part of the clean green image many tourists expect to see here. However, pollutants in the atmosphere can degrade visibility, especially near towns and cities. Usually visibility is affected by natural factors such as fog, sea salt particles or low cloud, but sometimes pollution from human activities decreases visibility by causing haze and smog. Sources of this pollution include emissions from vehicles, pollution from home fires and industrial activities.
The degradation of visibility has two main causes:
- light scattering by very fine particles
- light scattering and absorption by chemicals in the atmosphere, such as nitrogen dioxide.
For more information on visibility see the guide for monitoring and managing visibility in New Zealand published by the Ministry in 2001.
These pictures show a comparison of visibility degradation caused by winter smog (picture on the left) with clear spring air in Christchurch. Source: Canterbury Regional Council
Last updated: 17 July 2009
