fog, mist 是一種常見自然景象，成份是冷卻後的水蒸氣，
影響可視度，有時候身臨其境有美感。
haze 是一種非正常氣象現象，天氣預報應該報道，不但
嚴重影響可視度，同時刺激呼吸道黏膜危害人體健康。
The following is also a copy and past from Internet,
通過成份、位置和可見度把雲、霧和大霧給了比較好的解釋。
If your head is in the clouds, it is probably really in the fog.
Unless its in the mist! The difference between fog, mist
and cloud is less to do with its constitution, and more to do
with its location.
The fog is really just a low lying cloud, although its definition
is determined by its effect on visibility.When visibility is between
1000 and 5000 metres it is refered to as mist.Sometimes fog
can become so thick it can reduce visibility to only a few metres.
影響可視度，有時候身臨其境有美感。
haze 是一種非正常氣象現象，天氣預報應該報道，不但
嚴重影響可視度，同時刺激呼吸道黏膜危害人體健康。
The following is also a copy and past from Internet,
通過成份、位置和可見度把雲、霧和大霧給了比較好的解釋。
If your head is in the clouds, it is probably really in the fog.
Unless its in the mist! The difference between fog, mist
and cloud is less to do with its constitution, and more to do
with its location.
The fog is really just a low lying cloud, although its definition
is determined by its effect on visibility.When visibility is between
1000 and 5000 metres it is refered to as mist.Sometimes fog
can become so thick it can reduce visibility to only a few metres.
