What is Difference between Fog and Smog?

4,591 Views Updated: 14 May 2018
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What is Difference between Fog and Smog?
Answers (3)

Dear User,

Thank you for posting your query here. Many people confuse smog with fog. During winters, one may observe low grayish clouds in the sky and wonder if it is smog or fog. Both smog and fog look similar but both of them are formed in quite a different manner. The most basic difference between both of them is that fog is the result of accumulation of floating water droplets in the air while smog results from chemical toxins which are dispersed into the atmosphere. We have tried to explain other notable differences between fog and smog below:

#1. Definition
Fog: The accumulation of floating water droplets into the air is called fog. It consists of ice crystals or visible cloud water droplets which suspended in the air at or near the surface of the Earth.
Smog: Smog is a type of air pollutant which is a combination of fog and smoke. In fact, the word smog is a combination of two words i.e., ‘smoke’ and ‘fog’. Smog results from burning of coal in large amounts in an area. It is created by a mixture of sulfur dioxide and smoke.
#2. Formation
Fog: There are different types of fog, all of which form under varying circumstances. For eg. Radiation fog is formed at night. The air reached complete humidity as the Earth’s surface cools and radiation fog forms when surface heat is radiated into space. Another example could be of advection fog which forms when warm moist air moves over cold surface horizontally. Some other types of fog are sea fog, ice fog, freezing fog etc., all of which are formed under different conditions.
Smog: Smog is usually formed by burning of large amounts of coal in an area. As a result of coal burning, large amounts of smoke enter the atmosphere which when mixed with fog forms smog. Smog is basically caused by a mixture of sulfur dioxide and smoke.

#3. Effects
Fog: The primal effect of fog is hazardous driving conditions. Due to foggy weather, drivers find it difficult to see very far in front of them which results in a lot of accidents.
Smog: Smog causes a lot of harmful diseases as it contains air pollutants. Mostly, it is found to attack lungs and causes lung-related problems and diseases. Some of the diseases caused by formation of smog can be so harmful that a person can also die.

#4. Precautions
Fog: Fog causes low visibility which is a huge problem for the drivers. Therefore, it is advised to keep the speed of the vehicle under 40 mph and use low beams on the headlights so as to prevent any accident because of fog.
Smog: In order to protect oneself from smog, it is advised to use masks and stay in houses if the conditions are really worse. People are advised not to go on morning walks during smog as its effect is high in the morning.
We hope to solve your query and looking forward to more such interesting queries from your side.

Thanking You,
Team AskOpinion

(Image Courtesy: 1. IStock, 2. NDTV 3. Utne Reader, 4. Parent's Document)

Fog and smog are two very different thing which is by mistakes considered as a same thing sometimes. Fog happens when there is a lot of cold and the rays of sunlight is unable to come through the clouds which leads to a hind in low temperature. Smog on the other hand happens when there is a lot of pollution and that leads to blocking of sun rays which makes more or less the same kind of environment. This is the reason why smog and fog is usually confused to be the same thing. For is created by the moisture or the water droplets in the air whereas smog is created by the pollution bacteria. Fog never affects the breathing cycle of a human as it is just water droplets in the form of air whereas smog is extremely dangerous because it has polluting air in it. Therefore, they both are majorly different from each other.

Whenever a thick layer of gray air envelopes the city, we often call it fog! But is it really fog or is it smog?
With rise in the levels of pollution, it is becoming difficult to differentiate between smog and fog. When
we think its fog and the winters are approaching, that’s when the met department breaks our bubble
and informs us of hazardous smog. So, how do we differentiate between the two?
Well, let’s start with the basics. Although both result in low visibility, but there is a basic point of
differentiation between the two that makes it easy to understand the difference between the two. While
Fog is formed out of water droplets in the air, Smog is a result of pollution. If we look at it a little deeper,
you would understand the key difference between the two. Fog is composed of water droplets which
disperse light and lead to low visibility in the city. There are times when the visibility is not low but yet it
is hazy. That’s when you refer to it as mist. In short, mist is a milder term for fog. On the other hand,
Smog is an amalgation of smoke and fog. It is a result of polluted industrial wastes, automobile traffic,
sunlight and mild winds. This type of air can be hazardous and pose several serious health complications.
This leads us to the second point of difference which speaks of the effects of the two. Since fog is a result
of condensation and evaporation of water droplets, it poses no such threat to humans in terms of flu and
infections. Its only impact is felt on the visibility of the area. However, Smog is considered to be bad for
humans and becomes a root cause of a plethora of infections and breathing problems that can endanger
the lives of the human being.
Thus, one needs to stay protected from smog and take utmost care when exposed to the same. Try
wearing masks and stay indoors than gallivanting outside in the polluted environment, inhaling all the
toxic air.

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