ROCHESTER, N.Y. (WROC) — More recently, the National Weather Service in Buffalo has been issuing Special Weather Statements about potential locally dense fog for some of the counties in our viewing area, specifically for the early morning hours. Fog can cause visibility issues and could be potentially dangerous. With all of this talk about fog, did you happen to know that there are different types of fog? Let's break it down! First things first: What is fog? Defined by the National Weather Service Glossary, fog is "water droplets suspended in the air at the Earth's surface." The definition also goes on to say that fog can be hazardous when visibility is reduced to a quarter of a mile or less. It can often be described as a stratus cloud near the ground. So, how does fog form? Fog starts to develop when water vapor condenses. During the condensation, the molecules of water vapor combine to make tiny liquid water droplets that hang in the air. In order for the fog to form, dust or some kind of air pollution needs to be in the air. The water vapor then will condense around these pollution molecules. Depending on the level of humidity and temperature, fog can form very suddenly and then disappear just as quickly. The different types of fog There are several different types of fog. According to the National Weather Service, this is the list of different fogs: Radiation Fog Precipitation Fog Advection Fog Steam Fog Upslope Fog Valley Fog Freezing Fog Radiation Fog This type of fog forms when all of the solar energy exits the Earth and allows for the temperature to meet up with the dew point. The best condition for radiation fog to form is when it had just rained the previous night. This helps to moisten up the soil and create higher dew points. This makes it easier for the air to become saturated and form fog. However, wind speeds must be lighter than 15 mph to prevent the moist and dry air from mixing. Common characteristics of radiation fog includes Often patchy, shallow, and in low areas Lowest visibility around sunrise Usually dissipates around mid-morning Radiation fog will dissipate due to daytime heating. The surface air will start to warm up by conduction and will become unsaturated. Because of this, radiation will dissipate by the mid-morning. Credit: The National Weather Service Precipitation Fog Could also be referred to as rain induced fog. This type of fog forms when rain falls through cooler air. This is very common with warm fronts, but can occur with cold fronts if they are not moving too fast. The cold air and dryness at the surface while rain is falling through the air then evaporates. This causes the dew point to to rise and the saturation from that forms fog. Common characteristics of precipitation fog include: Persistent Covers wide areas Mostly occurs with warm or stationary fronts Fog forms on cold-air side of the front The dissipation of this type of fog is pretty simple. Once it stops precipitating, the formation stops and the fog begins to dissipate. Credit: Charlie's Weather Advection Fog This type of fog forms from the surface contact of horizontal winds, hence making this fog formation possible with windy conditions (unlike radiation fog). Warm, moist air blows in from the south and if there is snow or cool moisture on the ground, then it will come in contact with the warmer air. This contact between the warm air and cool ground will cause the air blowing in to cool down. This then rises dew points and create high humidity, therefore, forming fog. Common characteristics of advection fog include: Persistent Sometimes for days Covers a wide area Can form under a cloudy sky The main cause for advection fog to dissipate is the surface winds either cease or change direction. Unfortunately, the fog often continues, but rather just stops moving. Other ways we could potentially see dissipation is colder surface starts to warm and turbulent mixing above our heads starts to produce low ceilings instead of fog. Credit: The National Weather Service Steam Fog This type of fog is commonly seen in the Great Lakes, but can be seen on any lake. This type of fog typically forms during the fall season. As the summer closes out. water temperatures do not cool right away. However, air temperatures do. As a mass of dry, cold air moves over a warmer lake, the warm lake conducts warm, moist air into the air mass above. This transport between the lake and air eventually evens out. This corresponds tp the second law of thermodynamics, which states "any two bodies that come into contact, the system will become an equilibrium state." Steam fog does not become very deep, but usually deep enough to block out some sunlight. Common characteristics of steam fog include: Persistent Can be widespread Low-level convection present Convection is usually weak NOTE: The larger the body of water, the more persistent and widespread the fog The formation of steam fog typically ends when one of two things occur. It can end if the surface winds cease or change directions OR when the colder ground starts to warm on the windward side of the water. Credit: The COMET Program Upslope Fog This type of fog forms adiabatically. According to the National Weather Service, "adiabatically is the process that causes sinking air to warm and rising air to cool." As moist winds blow toward a mountain, it up glides and this causes the air to rise and cool. The cooling of the air from rising causes them to meet up with the dew point temperatures. Therefore, fog forms on the top of the mountains. Common characteristics of upslope fog include: Persistent Covers a wide area Can form under cloudy ckies Obscures hills and mountains Upslope fog will stop its formation when the surface winds cease or change direction and will dissipate when the downslope winds start to develop. Credit: Charlie's Weather Valley Fog Valley fog forms in the valley when the soil is moist from previous rainfall. as the skies clear, solar energy will exit the Earth and allow the temperature to cool near or at the dew point level. This forms deep fog, so dense it's sometimes called tule fog. Valley fog starts to evaporate within a few hours after sunrise, a process that is normally referred to as "burning off". Credit: The National Weather Service Freezing Fog Freezing fog occurs when the temperatures fall to or below 32°F (0°C). This fog produces drizzle and the tiny droplets freeze when they come in contact with an object, but there is also sublimation, the process of snow and ice changing into water vapor (gas) in the air without first melting into water, occuring at the same time. What types of fog could we see in Western New York? The types of that are typically seen here in Western New York are, but not limited to: Advection Fog Radiation Fog Steam Fog Precipitation Fog Fog Pictures! OK, this is cool! Check out the layer of fog that has developed over Canandaigua Lake. pic.twitter.com/FY64eKqdO6— Eric Snitil (@EricSnitilWx) April 5, 2023 So. Much. Moisture. The remnants of Debby have us feeling downright tropical this afternoon. All that moisture has resulted in layers of fog, as seen below from Sodus Point looking toward the Bluffs. pic.twitter.com/IkXa4AuTEQ— Eric Snitil (@EricSnitilWx) August 9, 2024 7am Fog! I don't see any other reports outside of what our camera is showing right now. I don't expect it to last much longer than an hour or so. pic.twitter.com/toM0GnA7uQ— James Gilbert (@JamesGilbertWX) April 19, 2024 Fall color and fog from Bristol Mountain this afternoon… pic.twitter.com/1vDGnxEXJQ— Eric Snitil (@EricSnitilWx) October 23, 2021 It's another day of morning fog! We are living in a cloud again in Rochester. The low-level moisture will linger into late this morning. pic.twitter.com/o8ijiaRBDm— James Gilbert (@JamesGilbertWX) May 16, 2024