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What’s The Difference Between Fog and Clouds?

An aerial view of a foggy forest.

When water vapor freezes or condolences to form small droplets or crystals in the air, both fog and clouds will form. In this way, both are very similar to one another.

With that being said, they both have distinct differences. For example, clouds can form at a wide range of altitudes, while fog can only form near the ground level. If you’re curious to know what additional characteristics separate fog and clouds, read on!

NOTE: To learn how clouds are formed, read our article “How do Clouds form?”.

Understanding What a ‘Cloud’ is

A cloud is a body of water that you can see and is high in the sky. When water evaporates, it goes in the sky or along the earth’s surface. This all depends on the direction of the wind and the pattern.

A view of the thick clouds from above.

If the water vapor is made in the sky and condenses high up then it will create a cloud. It goes around dust and smoke particles to make the clouds. They can also differ in weight and height.

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Understanding What ‘Fog’ is

When condensation happens near the surface of the earth, it creates fog or mist. It is a cloud that has just formed near the surface. What you feel when you walk through fog is what you feel walking through a cloud. The cold temperature and the unclearness are exactly what it would be like.

A foggy autumn day in the forest.

Fog vs. Mist: What’s The Difference?

Fog and mist are the same thing but have a difference when it comes to unclearness. If visibility is less than 1,000 meters then it is a fog. If visibility is greater than 1,000 meters it is called a mist.

What is Haze?

An aerial view of the skyscrapers of Hong Kong hidden behind haze.

Haze is different from the previous ones. Haze is tiny, dry particles that aren’t water but are things like dust or smoke. It is dust or smoke that is in the air and invisible to the naked eye. If it is dense enough to cause visibility issues, then it is a haze. These particles can sometimes cause the sky to red, which is seen during sunset.

Types of Fog

There are lots of types of fog, like radiation, advection, valley, and freezing.

Radiation Fog

An aerial view of a foggy landscape just before sunrise.

Radiation fog is when the heat on the surface of the Earth is put in the air during the evening. When the heat is transferred, water droplets are created. This can sometimes be called ground fog as well. It doesn’t go high into the air and is usually at night. The fog that burns off when the morning sun comes is radiation fog.

Advection Fog

A look at the fog over the mountain.

Advection happens when it is warm and moist in the air with a cool surface. This is called advection and describes how the fluid moves. The water vapor condenses in this scenario and creates the fog.

It usually happens in warm, tropical areas when the air meets the cool ocean. Usually, Washington to California is filled with advection fog. The California Current is cold and goes along the western coast of North America.

Valley Fog

This is an aerial view of a foggy valley.

Valley fog is in mountain valleys, normally during the winter season. Valley fog happens when mountains don’t allow the dense air from going anywhere. It is trapped in the valley. In 1930, it happened in the Meuse Valley in Belgium with particles of air pollution. Over 60 people died from this.

Freezing Fog

A view of a foggy street during winter.

Freezing fog is when liquid fog droplets freeze to surfaces that are solid. Mountaintops that have a lot of clouds usually have freezing fog. After it lifts, everything looks like spider webs with a layer of frost.

This usually happens in cold and moist places like Scandinavia or Antarctica. If the air doesn’t have any particles, the water in the air is “supercooled.” This means it is below freezing and can be dangerous when coming into contact with roads and sidewalks.

Super Fog

This is a view of a canal with very thick fog.

Super fog is when smoke from wildfires comes together with water vapor to make dense fog. The smoke gives particles for the water vapor to condense on. This is a dangerous fog because it is so dense that you couldn’t see your hand in front of your face. It also creates bad driving conditions.

Note: This can also be considered air pollution. To learn more about different types of air pollution, read our article “8 Different Types of Air Pollution”.

Pea Souper

A dirt road by the farm with very dense fog.

Pea souper is when water condenses around microscopic particles of coal. It is normally brownish-yellow and is common where coal is burned for energy.

How can we prepare for fog?

A lot of accidents happen every year because of fog. It also creates issues for airplanes. It can delay or cancel flights.

They can also get help from space, though. There are two types of satellites that NOAA monitors for fog. The first one is a geostationary satellite, which orbits Earth at the same rate as one rotation. This helps the satellite stay over a single location to give a bird’s eye point of view.

The second one is a polar satellite, which orbits over each pole. The Earth will rotate as these satellites move from pole to pole. It can see every part of the surface of the Earth. NOAA is starting a new generation of each of those satellites. They will be able to take high-resolution photos of fog and clouds. It can help pilots and drivers know where to expect fog.

Fog Catchers

A foggy forest with tall pine trees.

A lot of cultures collected water from fog in large pots under trees or shrubs. This was effective but not as good as collecting actual rainwater or other water.

Now, engineers have sophisticated ways of catching fog. Fog catchers are large screens that are put in arid areas. The water droplets form on the screens and into the collection containers below. One day, one screen can get 100 gallons of water.

Bellavista in Peru relies on fog catchers to get their water because they don’t have access to a lot. Every year, they have huge fog that comes in from the Pacific Ocean. In 2006, they got fog catchers outside of the town, Now the residents have enough water for everything.

Engineers have warned that fog catchers will only work in smaller areas. Despite this, engineers and politicians have worked together to find more powerful fog catchers that will reduce the need for people to need groundwater as much.

More About Clouds…