Radiation fog occurs in the United States and is a very common fog. It happens during the fall and winter. It is formed overnight as the air near the ground cools and stops flowing. The cooling helps the air to reach saturation and this is where the fog forms. Let us discuss the facts about how radiation fog develops in the valley at night and what causes radiation fog in detail.
1. How Radiation fog develops in the Valley at Night?
The radiation fog develops in the valley at night and on other low terrains. It is the instant cooling mixed with the calm nights and sheltered valleys which help them to form fog. In some parts of the United States such as the Central Valley in California, this radiation fog can be easily formed. (See 12 Facts about Fog Breath)
2. What causes Radiation Fog?
The radiation fog is formed in the evening due to the heat absorbed by the earth’s surface during the daytime is radiated into thick air. The heat is emitted from the ground to the air and therefore the water droplets form. People often use the term ground fog for radiation fog. (See How is dew formed?)
3. How does Valley Fog differ from Radiation Fog?
To know how does valley fog differ from radiation fog, take a look at the following:
- Radiation Fog: When there is a clear sky and calm weather, during winter, the earth’s surface releases thermal radiation after sunset. The layer above the ground cools down. It does not resist the capacity to hold water vapor which then condenses to form fog that is close to the ground. This is called radiation or ground fog. It occurs mostly in winter. It vanishes as soon as the ground gets warmer.
- Valley Fog: Valley fog is the type of radiation that happens for a particular duration. It is basically formed in the valleys or basins by hills and mountains. It develops when the mountains prevent the dense air from escaping the valleys. This fog is also formed during winters when the land cools and water vapor becomes the fog. Valley fogs can be dangerous because of their repeated nature.
4. What is a Freezing Fog?
Freezing fogs are formed when the temperature at the earth’s surface is below the freezing mark. If it is foggy in the morning the temperature stays 30°. This fog is developed out of supercooled cloud droplets. The tiny water droplets in the air are in liquid form as they are given to the air. (See What is air we breathe made up of?)
5. What Kind of Weather does Valley have?
Valleys can have interesting weather and the radiation fog develops in the valley at night. The river or stream flows through a valley, which increases the moisture. This combines with the cooler temperature at night which causes the valley fog and clouds. It has strong winds. The valley can filter the air which flows between the tall buildings. This could be the result of the nice valleys that surround the area. (See What would You expect from an Unstable Air Mass?)
6. What is the Difference between Fog and Mist?
- Fog: Fog is the name given to that which results in less clarity than 1 km. According to the public forecast, this refers to less clarity than 180 m.
- Mist: Mist is defined as the visibility which is equal to 1000 m. This also happens due to the water droplets at a lower density.
7. Which is the Foggiest Area in The United States?
8. What Precautions must be taken While driving in Fog?
Fog defeats the clarity outdoors, and it produces dangerous driving conditions. We must always be cautious while driving in low-land areas near water when fog occurs.
- Put your headlights on and use low beams.
- Don’t get distracted while driving.
- Drive slowly and leave enough space between other cars and yours.
- Always be careful about cold temperatures.
- Always study the precautions.
9. What Kind of Fog is seen in the Coastal Area?
Mostly upslope fog can be seen on the hillsides and coastal areas. When the air rises from above, it is cooled. The pressure changes the air, and it becomes temporarily saturated where this fog can actually disappear. The air can drop back to its normal height and temper.
There was a particular type of radiation fog known as tule. Radiation fog usually occurs in California during the winter months in the United States. They are a blend of chilly Pacific Ocean surface air. The fog will travel upward as soon as the air becomes cooler. Valleys without any wind or other bodies of water are where these events occur most frequently. I hope it was useful; this was all about the radiation fog and how radiation fog develops in the valley at night. (See How elevation affects climate?)