What Is Fog?

• Fog is essentially a stratus cloud that has touched the earth, so fog is formed in much the same way as a cloud.
  
  

How Are Clouds and Fog Formed?

• When water evaporates from the ocean, rivers and other bodies of water, it evaporates as water vapor. That water vapor is a gas. As it rises up in the air, it can bond to dust particles or any other type of microscopic pollutant. This causes water droplets. When the water droplets group together, you get a cloud or some fog. Mist is also the same as fog, but it is not as thick.
  
  

What Conditions Need to Be Met to Get Fog?

• Fog occurs when the humidity is close to 100 percent, but not at 100 percent. Fog also needs the difference between the air temperature and the dew point to be 5 degrees F or less. Under these conditions, when water droplets are on their way up to the clouds, they will bond together close to the earth and form fog.