Difference Between Clouds and Fog (with Table)

Whenever we look at the sky we see a white cotton-like thing scattered in the sky that looks marvelously beautiful and this beautiful thing is known as Cloud. Clouds are an important part of the water cycle. These clouds can form at different altitudes. They can be high as 20 km above the sea level and even low as the ground. So, the form of cloud which is low as the ground is known as Fogs. Fogs appear in the winter season and restrict our vision. 

Clouds vs Fog

The difference between fog and clouds is that Clouds form when the water vapor (a gaseous form of water) turns into liquid and form on tiny particles like dust whereas fog is formed when the air near the ground cools enough to turn its water vapor into liquid water or ice.

Also, clouds can form at any altitude and are present in any climate whereas fog can only form at ground level and are present during cold climatic conditions only.

Comparison Table Between Clouds and Fog

Parameter of ComparisonClouds Fog
AltitudeClouds are present at any altitude.Fog is present at ground level only.
SignificanceClouds are significant because they contribute to the water cycle.Fog is not so significant.
ExistenceThroughout the year.Winters only.
density0.5g/m30.05g/m3 – 0.5g/m3
Occurrence of condensationCondensation occurs high in the atmosphere.Condensation occurs close to the ground.
Precipitation of Water backClouds precipitate water back in the form of rain.Fog doesn’t precipitate water back. 

What are Clouds?

Clouds are a mass of ice crystals or water drops suspended in the atmosphere. They are an important part of the water cycle. They also contribute to Earth’s weather and climate. There are 10 types of clouds classified into 3 different levels:

  • High-Level Clouds: There are three high-level clouds:
  1. Cirrus(Ci): This type of clouds often appear like white patches in the sky. Cirrus is made up of ice crystals and they appear bright yellow or red before sunrise and after sunset.
  2. Cirrocumulus(Cc): This type of cloud is like a thin white patch or sheet layered in the sky without shading. They appear as small elements arranged randomly.
  3. Cirrostratus(Cs): This type of cloud is transparent and more like a white veil or a sheet of white butter paper. It is not opaque enough to block sun rays.
  • Mid-Level Clouds: There are three types of mid-level clouds:
  1. Altocumulus (Ac): They have a grey and white patch like or layered sheet-like appearance. Most of the small elements arranged in this type of cloud constitute a width of a little finger.
  2. Altostratus (As): They are somewhat greyish -bluish kind of sheets or layers that covers the sky totally or partially. They are translucent.
  3. Nimbostratus (Ns): These are dark grey colored cloud layer which gets diffused by falling rain or snow. They are opaque and don’t allow sunlight to pass through it. 
  • Low-Level Clouds: There are four types of low-level clouds:
  1. Cumulus (Cu): There are dense clouds with sharp outlines that get developed in the form of towers, buildings.
  2. Cumulonimbus (Cb): This is the thunderstorm cloud. It is huge, dense, and appears like a mountain. 
  3. Stratocumulus (Sc): These are like grey or whitish colored patch or sheet-like layered clouds that have a dark honeycomb-like appearance. 
  4. Stratus (St): These are grey clouds with a uniform and dense layer. They produce ice prisms, snow grains, etc.

Clouds are formed when water from the ground or any water body gets evaporated in the form of water vapor by trapping the heat and leaving the water behind them cooler. Then this water vapor forms on the dust particles present in the air forming water drops by the method of condensation and such water drop combine to form clouds.

What is Fog?

Fog is a form of cloud which consists of tiny water droplets or ice crystals suspended in the air near the earth’s surface and it is influenced by water bodies, climate, etc.

There are 8 types of fogs present, they are:

  1. Radiation Fog: This fog forms when there is no presence of solar energy on the earth’s surface and the temperature can meet the dew point.
  2. Precipitation Fog: This fog forms in the presence of rain and cold air. This is common with warm fronts but it occurs with cold fronts as well.
  3. Advection Fog: This fog forms in windy conditions, that is, due to contact of horizontal winds with the surface.
  4. Steam Fog: This fog is commonly seen in lakes and it occurs during the autumn season.
  5. Upslope Fog: This fog forms by the process in which the sinking air warms up and the rising air cools down.
  6. Valley Fog: It forms in the valley in the moist soil which is due to previous rainfall. It is also known as tule fog.
  7. Freezing Fog: It occurs when the temperature is as less as 0℃ or below. The tiny droplets present in this fog freeze around the object when they come in contact.
  8. Ice Fog: This type of fog is present only in very cold regions like polar and arctic regions where the temperature is even less than -10℃.

Fog is formed when the water vapor formed during evaporation gets condensed at ground level itself because of cool air.

Main Differences Between Clouds and Fog

  1. Clouds form when condensation takes place at a high altitude whereas fog is formed when condensation occurs at ground level. Clouds are may be present at any altitude but fog is present only at ground level.
  2. Clouds are significant because they contribute to the water cycle whereas fog isn’t so significant.
  3. Clouds are present throughout the year and all the places whereas fog is present in the winter season and cold places only.
  4. The density of clouds is 0.5g/m3 whereas the density of fog is 0.5g/m3- 0.05g/m3.
  5. Clouds precipitate the absorbed water back to the earth in the form of rain but the fog doesn’t precipitate.


Fog is basically a type of cloud which exists at the ground level and the cloud can exist at any altitude. The fog gets limited to ground level because in cool air the condensation takes place at ground level itself.


  1. https://link.springer.com/article/10.1023/A:1006611609450
  2. https://www.researchgate.net/profile/Tobias_Hossfeld/publication/235437099_FoG_and_Clouds_Optimizing_QoE_for_YouTube/links/5444eff80cf2e6f0c0fbf624.pdf