What is fog？

Have you ever walked out of your front door in early morning and faced a thick covering of white air that prevented you from seeing more than a few feet in front of you？ This is known as a fog. It is actually a type of stratus cloud but is called by a different name because it forms by a different process.

什么是霧？

你曾经有过在清晨走出门，面对一层厚厚的白茫茫的空气，看不到前面几英尺开外的地方的经历吗？这就是所谓的雾。它实际上是一种层云，但由于不同的形成过程，它被冠以的不同的名称。

How is fog formed？

A stratus cloud is any low-lying cloud that makes the atmosphere hazy. Like all clouds， they are formed when water vapour condenses when it rises to a cooler part of the earths atmosphere. However， a fog is different because the water vapour reaches its dew point （the temperature at which it turns back into water droplets） right over the surface of the earth. We cannot see water vapour because it is a gas， but when it turns back into water droplets， it becomes visible to the eye. This rapid cooling just over the ground could be caused by a number of reasons.

雾是怎么形成的？

层云是使大气朦胧的低云。和所有的云一样，它们是在水蒸气上升到地球大气层较冷的地方时凝结而成的。然而，雾是不同的，因为水蒸气达到露点（它变成水滴的温度）是在接近地面的地方。我们看不到水蒸气，因为它是一种气体，但当它变成水滴时，它就变得肉眼可见了。地面上的这种快速降温可能是多种原因造成的。

What causes fog？

Falling rain can cool down the water vapour and cause it to remain suspended close to the ground as a fog.

When there is a big difference between the temperatures of the day and night， the land continues to lose the heat it absorbed during the day. The cool night air sandwiches the water vapour close to the ground resulting in a fog.

Finally， when warm， moist air blows over a cold surface like ice or snow， it cools it down rapidly and turns to fog.

雾的成因是什么？

下雨可以使水蒸气降温，并使其像雾一样悬浮在靠近地面的地方。

当昼夜温差较大时，土地白天吸收的热量持续流失。夜间的冷空气把靠近地面的水蒸气夹在中间，形成了雾。

最后，当温暖潮湿的空气吹过像冰或雪一样冷的表面时，它会迅速冷却并变成雾。

Fog and mist

You may wonder what the difference between fog and mist is. Well they are actually one and the same. A mist is simply a fog that isnt very thick.

Fog and mist are both created by water droplets， differing only in their overall locations and density. Fog is a cloud that reaches ground level， even if that “ground” is a hill or mountaintop. Mist forms wherever water droplets are suspended in the air by temperature inversion， volcanic activity， or changes in humidity. Fog is denser than mist and tends to last longer. In terms of visibility， fog reduces it to less than one kilometer， while mist can reduce visibility to between 1 and 10 kilometers.

The exact definition is if you cannot see an object that is less than 1 km in a mist， it is considered a fog.

雾与霭

你可能会想雾和霭有什么区别？其实它们是一样的。霭只是一种不太浓的雾。

雾和霭都是由水滴形成的，只是它们的整体位置和密度不同。雾是到达地面的云，即使“地面”是山丘或山顶。由于气温逆增、火山活动或湿度变化，水滴悬浮在空气中会形成霭。雾比靄更浓，而且往往持续时间更长。在能见度方面，雾使能见度降低到1千米以下，而霭则使能见度降低到1至10千米。

确切的定义是，如果你在雾霭中看不到距离小于1千米的物体，那那就是雾。……