Definition of MIST Water in the form of particles, floating or falling in the atmosphere at ‘or’ near the surface of the earth and approaching in the form of rain. What causes fog? Fog can be considered a cloud at ground level. The processes forming it, however, are usually different from those that form clouds. Like clouds, fog is made up of condensed water droplets which are the result of the air being cooled to the point (actually, the dew-point) where it can no longer hold all of the water vapour it contains. For clouds, that cooling is almost always the result of rising of air, which cools from expansion. But for fog, which occurs next to the ground, there are usually other reasons for this cooling. For instance, rain can cool and moisten the air near the surface until fog forms. Or, as is more often the case, infrared cooling of a cloud-free, humid air mass at night can lead to fog formation - this is called "radiation fog". Radiation fog is most common in the fall, when nights get longer, air masses begin to cool, and land and water surfaces that have warmed up during the summer are still evaporating a lot of water into the atmosphere. Finally, a warm moist air mass blowing over a cold surface (usually snow or ice, or over a cold ocean surface) can also cause fog to form-this is called "advection fog". Haze: is traditionally an atmospheric phenomenon where dust, smoke and other dry particles obscure the clarity of the sky. The World Meteorological Organization manual of codes includes a classification of horizontal obscuration into categories of fog, ice fog, steam fog, mist, haze, smoke, volcanic ash, dust, sand and snow.[1] Sources for haze particles include farming (ploughing in dry weather), traffic, industry, and wildfires.
Posted on: Tue, 02 Jul 2013 07:52:19 +0000
Trending Topics
Recently Viewed Topics
© 2015