[0:00]In this video, we're going to look at all seven types of fog that you should know as a pilot. We'll dive into exactly how and where they happen so that you can avoid getting caught by it.
[0:09]Now, can you name all seven of them? My name is Greg. I've been an FA flying structure for over 20 years, and I'm also the lead instructor at Pilot Institute, the online school that helps you achieve your aviation dreams.
[0:20]First, what is fog? In a nutshell, fog is a low-lying cloud. It's tiny little water droplets that are near the earth's surface that cause reduced visibility.
[0:31]Fog forms when the air temperature reaches the due point. It's very important. This causes the water vapor to become visible droplets.
[0:39]Fog, very much like other clouds, is going to hamper visibility and is going to directly impact visual flying.
[0:46]But what's the difference between other types of visibility restriction, like mist, for example? Well, if the visibility is less than 5/8 statute mile, then it's called fog. If the visibility is greater than 5/8 statute mile, then it's going to be called mist.
[0:59]Now, we classify the different types of fog according to how they form, which brings us to the first type of fog. It's called radiation fog.
[1:07]Now, radiation fog usually forms at night when the surface cools, causing the air above it to cool as well. Now, if the air has enough moisture, this cooling will lead to saturation and then form fog.
[1:20]Now, this type of fog is also known as ground fog if it's less than 20 feet thick. You'll find radiation fog early in the morning when the surface is coldest.
[1:29]Now, it tends to dissipate soon after sunrise and as the ground is going to warm. Now, because of this, many people call radiation fog "morning fog."
[1:37]Now, there are three different conditions that lead to the formation of radiation fog. The first is a clear sky. Now, clouds will trap the heat from the surface, causing it and the air above it to stay warmer.
[1:49]So, a clear sky is going to cause the maximum amount of cooling effect. Now, second, we need to have calm winds. This allows for an uninterrupted cooling of the air.
[1:59]Now, third, we need to have a long night. Long nights, just like those in the winter, they allow for the surface to cool and then for the air to cool above it for the longest period of time.
[2:10]Now, high-pressure systems often create the conditions that lead to that radiation fog. The next type of fog is called advection fog. Now, advection fog forms when the warm and moist air moves over a cooler ground or over water.
[2:27]Now, it is relatively shallow and it's often associated with a temperature inversion. Now, unlike radiation fog, advection fog can actually form with strong winds and also with cloud cover.
[2:37]Now, another type of fog that is associated with the wind is called the upslope fog. Upslope fog is going to form when the moist air flow is going to go upward over the rising terrain, causing it to cool using a method called adiabatic in order for the due point temperature to be reached.
[2:54]Now, adiabatic is the process that causes the rising air to cool and the sinking air to warm. Now, this type of fog is more common at higher elevations and also can build downward into the valleys.
[3:07]Upslope fog can also exist in high-wind conditions, because, well, that's going to increase the lift and then also increase the adiabatic cooling.
[3:15]Next up is steam fog. Steam fog is also known as evaporation fog, and that is going to form when a cold air is going to move over a warm body of water. Warmer water is going to evaporate into the cooler air above it, and then increase the air moisture content.
[3:32]When the moist, warm air is cooled to the due point temperature by the cooler air below it, then the warm vapor is going to condense into tiny water droplets, and that's going to create fog.
[3:44]Now, this often happens in the early fall or the late spring, when the air temperature is going to drop quickly compared to the actual water temperature. So, what does the steam fog actually look like? Well, it's a wispy tendrils that are rising from the water surface, that can resemble steam.
[4:00]Hence, what we call it steam fog. Now, you'll often find the steam fog over bodies of water such as lake, rivers, and then reservoirs.
[4:08]Okay, now things are getting a little colder with freezing fog and ice fog. Freezing fog forms in saturated air when the surface temperature is below freezing. Now, the water droplets in freezing fog are actually called supercooled, which means that they are in the liquid state despite being below freezing temperature.
[4:26]So, the reason they do not freeze in the air is because they don't have the nucleus of the core around which the ice crystal can actually form. Now, freezing fog is more common in regions where the winters are really cold, especially in the valleys or any areas where the cold air is going to be stagnant.
[4:42]Now, the freezing temperatures cause the supercooled water droplets to freeze on impact with any surfaces. That creates rime ice either on the ground or possibly on your wing. That's important to differentiate between freezing fog and ice fog.
[4:57]Ice fog resembles freezing fog, but it consists of tiny little ice crystals and then happens when we have extremely cold conditions, well below the 32 Fahrenheit or the 0 degrees Celsius.
[5:09]Now, freezing fog, on the other hand, contains liquid water droplets. This is going to form around temperatures that are right around or just below freezing.
[5:17]The second to last type of fog is called frontal fog. Frontal fog is going to form during a warm or a cold front passage. The warmer rain that falls into the colder air is going to then evaporate.
[5:28]As a result, the due point is going to rise, and then that's going to lead to air saturation. Now, the fog associated with a warm front is called pre-frontal, and then the fog associated with a cold front is called post-frontal.
[5:39]Frontal fog usually dissipates right after the front passes. The last type of fog that you may encounter is called precipitation fog.
[5:46]This type of fog is going to form when the rain falls through a cold and dry air mass. The increased moisture leads to an increase in due point, causing the saturation and the formation of fog.
[5:57]A precipitation fog is associated with a warm front and can also result from a slower moving cold front. From a flying perspective, fog is a real pain, especially when flying VFR. It's not as much of an issue if you're flying IFR.
[6:09]Check out this uncut video right here from one of our IFR flight with one of our flight instructor, and thanks for watching. We'll see you in the next one.
