云里雾里,解释一下

 

Cloud vs Fog

 

Cloud and fog are natural phenomenons. Clouds are one of the most common weather phenomenons and found in the skies all over the world. It is unimaginable to think of skies without clouds. Clouds play a vital role in weather cycle and are also objects of beauty as any skyline looks sensational only because of white, silvery clouds across blue skies. Fog is another weather phenomenon that looks just like clouds but at a very low level that is almost at the surface of earth. This is why many people remain confused and think of clouds and fog as being same. However, this is not so and there are differences that will be talked about in this article.

Clouds

Clouds are formed because of condensation of water vapor present in air. Condensation is the process that allows water vapor in air to be converted into liquid water. Formation of clouds full of moisture is crucial for water cycle as they precipitate and give out much needed water in the form of rains on earth. In water cycle, condensation is just the opposite of evaporation that takes away water from the surface of the earth.

If you do not see clouds up in the skies (clear blue skies), it does not indicate absence of water. Water is still there in the form of water vapor and small droplets that cannot be seen. When these water droplets get to mix with particles of dust, salt, and smoke, they grow in size and develop into clouds. There are different sizes of droplets in clouds and their size can vary from as small as 10 microns to as large as 5 mm. Air high up in the atmosphere is cooler and more condensation takes place there. With water droplets coalescing with each other, clouds begin to form and may even precipitate.

Fog

It is not that condensation takes place only high up in the atmosphere, and when condensation occurs at ground level, fog is formed. Fog is a phenomenon that makes us experience what clouds are like and we do need not fly on hot air balloon to go up on clouds. In this case, air laden with moisture (high humidity) comes in contact with colder surface such as earth and cools down to its dew point. When a bit more cooling takes place, condensation occurs that results in low level clouds that we call fog. Another way through which fog gets formed is when warm air moving over a colder surface creates advective fog. Hence there is no difference between clouds and fog, and fog is essentially low level clouds.

In brief: Difference Between Cloud and Fog • Condensation of water vapor present in air, whether high up in the skies, or near the surface of earth, leads to formation of clouds. But whereas we are more familiar with clouds across the blue skies, the ones that are formed near the surface of earth are called fog. • When water vapor in air condenses into tiny droplets of water, fog is formed • Fog is more or less a distant cousin of much more fancied clouds.

Read more: http://www.differencebetween.com/difference-between-cloud-and-vs-fog/#ixzz2kdqmk5AB

所有跟帖： 

• 谢解释。可我不明白"Thank vs.truth,xie4 vs.li3"。 -婉蕠- ♀ (0 bytes) () 11/14/2013 postreply 10:08:45

• "謝-理"解釋，我書將揭 -走马读人- ♂ (0 bytes) () 11/14/2013 postreply 10:42:06

• 预祝你的书早日出版。 -婉蕠- ♀ (0 bytes) () 11/14/2013 postreply 19:22:01

• Thx! 計劃春節1.31.2014前結束。 -走马读人- ♂ (0 bytes) () 11/14/2013 postreply 21:04:08

• Time flies. 转眼又将是一年了。 -婉蕠- ♀ (0 bytes) () 11/15/2013 postreply 07:20:12