I'm sure you've wondered at some point what fog is, right? It's a question many of us ask ourselves, even as children when we wake up to find our neighborhood has become a ghost town. Well, in this special feature, I'm not just going to talk about fog, but also about mist , since the two concepts are often confused.
This way, when they happen again, you'll know the difference between fog and mist.
What is fog?
Fog is a hydrometeor , that is, a collection of water particles, liquid or solid, falling, suspended in the atmosphere, or lifted from the Earth's surface by the wind, or deposited on objects on the ground or in the free atmosphere. It produces visibility of less than 1 km. These water particles are not large enough for gravity to cause them to fall, so they usually remain suspended.
How is it produced?
Especially during December and January in Spain, fog is a common feature at dawn in many regions. It forms in situations of absolute stability, when an anticyclone is present and there is no wind. This occurs when the temperature in the lower layers of the atmosphere is lower than in the upper layers, or in other words: when it is colder at the beach than in the mountains.
Types of fog
Although we might think that the fog is always the same in all places, the reality is that different types are distinguished:
- Radiation: which is what we see after sunset on a cloudless night, in autumn. It is one meter thick and does not last long.
- Of Earth: it is a radiation fog, but very superficial. It darkens less than 60% of the sky and does not extend to the base of the clouds.
- Advection: When masses of hot, moisture-laden air pass over cold soils, this type of fog is produced. It is very common on the coasts.
- Steam: appears when cold air passes over warm waters. This fog in which we can see in the polar regions.
- Precipitation: If it starts to rain and the air under the cloud is dry, our visibility will surely be reduced.
- Hillside: It is formed when the wind blows against the side of a mountain.
- From valley: this type of fog is the result of thermal inversion, caused by cold air that remains in the valley, while warmer air passes over it.
- Of ice: It occurs when frozen water droplets are suspended above the ground. It is very common in the polar regions.
- Upward sloping: occurs when there is a drop in pressure with altitude.
Is it dangerous to health?
No, not at all. People often think that it can harm us, but the truth is that fog itself isn't harmful. The only difference between the air you'll breathe and the air we breathe on any other day is that it contains a higher concentration of water vapor.
But you should keep in mind that there will be much more pollution on those days because there won't be any wind, so if you have allergies, you might notice your symptoms worsen a bit. And by the way, if you're going to drive, be very careful on the road.
What is haze?
Now that we've seen what fog is, let's look at what mist is. Well, mist is also a hydrometeor, composed of very small water droplets, between 50 and 200 micrometers in diameter. They reduce horizontal visibility to a distance of one kilometer or more.
It occurs naturally by atmospheric processes or the result of volcanic activity, and occurs frequently when in the atmosphere there is a cold air mass under a temperate one. In mist the air generally does not feel sticky and humid and the relative humidity is well below 100 percent. Another of its characteristics is that it forms a little dense grayish / bluish veil that covers the landscape.
And how is mist different from mist?
Mist at dawn
They are basically distinguishable by sight. Let me explain: fog doesn't allow you to see beyond 1 km, while mist does. Furthermore, the air in a fog bank is sticky and humid , as the relative humidity approaches 100%.
We'll also know it's fog when we can't see the sun's rays . Mist, being less dense, will allow us to see them without too much trouble; whereas with fog, that will be impossible.
I hope I have clarified your doubts about these two meteorological phenomena that amaze children and adults so much.