So, what is fog???

Big Daddy

Super User
This stuff looks more like smog to me-- the stuff that contains toxins that increase risk for lung cancer. Smog is found all major and industrial cities in India as a result of pollution. Here is the difference between smog and fog <Smog and Fog Differences by James Johnson | Sciences 360 >, confusing between the two means difference between two things that support life and death.

Here is what smog is doing to Indians:

A study published in the Lancet medical journal in October showed the lung capacity of nonsmoking Indian adults is just two-thirds that of North America and Europe. The study did not analyze various factors, from pollution to nutrition, that might account for the difference, but doctors unaffiliated with the study said they believed air pollution was likely a major cause.


Source: http://bigstory.ap.org/article/wide-gap-between-new-delhi-beijing-smog-policies
 
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This stuff looks more like smog to me-- the stuff that contains toxins that increase risk for lung cancer. Smog is found all major and industrial cities in India as a result of pollution. Here is the difference between smog and fog <Smog and Fog Differences by James Johnson | Sciences 360 >, confusing between the two means difference between two things that support life and death.

Here is what smog is doing to Indians:

A study published in the Lancet medical journal in October showed the lung capacity of nonsmoking Indian adults is just two-thirds that of North America and Europe. The study did not analyze various factors, from pollution to nutrition, that might account for the difference, but doctors unaffiliated with the study said they believed air pollution was likely a major cause.


Source: Wide gap between New Delhi, Beijing smog policies
The stuff you see here is fog alright. The Keola Deo National park is not very close to any major industry. The amount of water in the wetlands is what predisposes to fog, given the right temperatures.

You are right about the effect that smog has, mainly in industrial belts, in India.
 

adsatinder

explorer
Fog in North India normally happens
when temperature drops near 9 Degree Celcius with humidity crossing 80% approx. around water bodies.



Fog screens out chill
Experts say fog occurs when the
air becomes saturated with moisture and the
temperature is less than the dew point —
the temperature at which water vapour in a volume of humid air condenses into water.

“Higher the temperature, higher the capacity of the air to hold water vapour. So when the temperature drops, at dawn or in the evening, there tends to be fog,” said a weather department official.








Fog - Wikipedia, the free encyclopedia
Definition
The term "fog" is typically distinguished from the more generic term "cloud" in that fog is low-lying, and the moisture in the fog is often generated locally (such as from a nearby body of water, like a lake or the ocean, or from nearby moist ground or marshes).[2]

By definition, fog reduces visibility to less than 1 kilometre (0.62 mi), whereas mist causes lesser impairment of visibility.[3]

For aviation purposes in the UK, a visibility of less than 5 kilometres (3.1 mi) but greater than 999 metres (3,278 ft) is considered to be mist if the relative humidity is 70% or greater; below 70%, haze is reported.[4][broken citation]





Formation
See also: Cloud physics
Fog forms when the difference between air temperature and dew point is generally less than 2.5 °C or 4 °F.[5]

Fog begins to form when water vapor condenses into tiny liquid water droplets suspended in the air. The main ways water vapor is added to the air: wind convergence into areas of upward motion;[6] precipitation or virga falling from above;[7] daytime heating evaporating water from the surface of oceans, water bodies, or wet land;[8] transpiration from plants;[9] cool or dry air moving over warmer water;[10] and lifting air over mountains.[11] Water vapor normally begins to condense on condensation nuclei such as dust, ice, and salt in order to form clouds.[12][13] Fog, like its elevated cousin stratus, is a stable cloud deck which tends to form when a cool, stable air mass is trapped underneath a warm air mass.[14]

Fog normally occurs at a relative humidity near 100%.[15] This occurs from either added moisture in the air, or falling ambient air temperature.[15] However, fog can form at lower humidities, and fog can sometimes fail to form with relative humidity at 100%. A reading of 100% relative humidity means that the air can hold no additional moisture; the air will become supersaturated if additional moisture is added.

Fog can form suddenly, and can dissipate just as rapidly, depending whether the temperature is below or above the dew point, respectively. The sudden formation of fog is known as "flash fog".[16]

Fog commonly produces precipitation in the form of drizzle or very light snow. Drizzle occurs when the humidity of fog attains 100% and the minute cloud droplets begin to coalesce into larger droplets.[17] This can occur when the fog layer is lifted and cooled sufficiently, or when it is forcibly compressed from above by descending air. Drizzle becomes freezing drizzle when the temperature at the surface drops below the freezing point.

The thickness of a fog layer is largely determined by the altitude of the inversion boundary, which in coastal or oceanic locales is also the top of the marine layer, above which the airmass is warmer and drier. The inversion boundary varies its altitude primarily in response to the weight of the air above it which is measured in terms of atmospheric pressure. The marine layer and any fogbank it may contain will be "squashed" when the pressure is high, and conversely, may expand upwards when the pressure above it is lowering.





Types
Fog can form in a number of ways, depending on how the cooling that caused the condensation occurred.

Radiation fog is formed by the cooling of land after sunset by thermal radiation in calm conditions with clear sky. The cool ground produces condensation in the nearby air by heat conduction. In perfect calm the fog layer can be less than a meter deep but turbulence can promote a thicker layer. Radiation fogs occur at night, and usually do not last long after sunrise, though can persist all day in the winter months especially in areas bounded by high ground such as the Vale of York in England. Radiation fog is most common in autumn and early winter. Examples of this phenomenon include the Tule fog.[18]

Ground fog is fog that obscures less than 60% of the sky and does not extend to the base of any overhead clouds.[19] However, the term is usually a synonym for radiation fog.


Advection fog layer in San Francisco with the Golden Gate Bridge and skyline in the background
Advection fog occurs when moist air passes over a cool surface by advection (wind) and is cooled.[20] It is common as a warm front passes over an area with significant snow-pack. It is most common at sea when moist air encounters cooler waters, including areas of cold water upwelling, such as along the California coast (see San Francisco fog).

The advection of fog along the California coastline is propelled onto land by one of several processes. A cold front can push the marine layer coast-ward, an occurrence most typical in the spring or late fall. During the summer months, a low pressure trough produced by intense heating inland creates a strong pressure gradient, drawing in the dense marine layer. Also during the summer, strong high pressure aloft over the desert southwest, usually in connection with the summer monsoon, produces a south to southeasterly flow which can drive the offshore marine layer up the coastline; a phenomenon known as a "southerly surge", typically following a coastal heat spell. However, if the monsoonal flow is sufficiently turbulent, it might instead break up the marine layer and any fog it may contain. Moderate turbulence will typically transform a fog bank, lifting it and breaking it up into shallow convective clouds called stratocumulus.

Precipitation fog (or frontal fog) forms as precipitation falls into drier air below the cloud, the liquid droplets evaporate into water vapor. The water vapor cools and at the dewpoint it condenses and fog forms.

Hail fog sometimes occurs in the vicinity of significant hail accumulations due to decreased temperature and increased moisture leading to saturation in a very shallow layer near the surface. It most often occurs when there is a warm, humid layer atop the hail and when wind is light. This ground fog tends to be localized but can be extremely dense and abrupt. It may form shortly after the hail falls; when the hail has had time to cool the air and as it absorbs heat when melting and evaporating.[21]





Freezing conditions
Freezing fog occurs when liquid fog droplets freeze to surfaces, forming white soft or hard rime.[22] This is very common on mountain tops which are exposed to low clouds. It is equivalent to freezing rain, and essentially the same as the ice that forms inside a freezer which is not of the "frostless" or "frost-free" type. The term "freezing fog" may also refer to fog where water vapor is super-cooled, filling the air with small ice crystals similar to very light snow. It seems to make the fog "tangible", as if one could "grab a handful".

Frozen fog (also known as ice fog) is any kind of fog where the droplets have frozen into extremely tiny crystals of ice in midair. Generally this requires temperatures at or below −35 °C (−31 °F), making it common only in and near the Arctic and Antarctic regions.[23] It is most often seen in urban areas where it is created by the freezing of water vapor present in automobile exhaust and combustion products from heating and power generation. Urban ice fog can become extremely dense and will persist day and night until the temperature rises. Extremely small amounts of ice fog falling from the sky form a type of precipitation called ice crystals, often reported in Barrow, Alaska. Ice fog often leads to the visual phenomenon of light pillars.

The phenomenon is also extremely common in the inland areas of the Pacific Northwest, with temperatures in the 10 to 30 °F (−12 to −1 °C) range. The Columbia Plateau experiences this phenomenon most years due to temperature inversions, sometimes lasting for as long as three weeks. The fog typically begins forming around the area of the Columbia River and expands, sometimes covering the land to distances as far away as LaPine, Oregon, almost 150 miles (240 km) due south of the river and into south central Washington.





Topographical influences
Up-slope fog or hill fog forms when winds blow air up a slope (called orographic lift), adiabatically cooling it as it rises, and causing the moisture in it to condense. This often causes freezing fog on mountaintops, where the cloud ceiling would not otherwise be low enough.

Valley fog forms in mountain valleys, often during winter. It is essentially a radiation fog confined by local topography, and can last for several days in calm conditions. In California's Central Valley, valley fog is often referred to as Tule fog.





Sea and coastal fog
Sea fog (also known as haar or fret) is heavily influenced by the presence of sea spray and microscopic airborne salt crystals. Clouds of all types require minute hygroscopic particles upon which water vapor can condense. Over the ocean surface, the most common particles are salt from salt spray produced by breaking waves. Except in areas of storminess, the most common areas of breaking waves are located near coastlines, hence the greatest densities of airborne salt particles are there.

Condensation on salt particles has been observed to occur at humidities as low as 70%, thus fog can occur even in relatively dry air in suitable locations such as the California coast. Typically, such lower humidity fog is preceded by a transparent mistiness along the coastline as condensation competes with evaporation, a phenomenon that is typically noticeable by beachgoers in the afternoon. Another recently discovered source of condensation nuclei for coastal fog is kelp seaweed. Researchers have found that under stress (intense sunlight, strong evaporation, etc.), kelp releases particles of iodine which in turn become nuclei for condensation of water vapor, causing fog that diffuses direct sunlight.[24]

Sea smoke, also called steam fog or evaporation fog, is the most localized form and is created by cold air passing over warmer water or moist land.[22] It often causes freezing fog, or sometimes hoar frost.

Arctic sea smoke is similar to sea smoke, but occurs when the air is very cold. Instead of condensing into water droplets, the water vapor desublimates directly into ice crystals.

Garua fog near the coast of Chile and Peru,[25] occurs when typical fog produced by the sea travels inland, but suddenly meets an area of hot air. This causes the water particles of fog to shrink by evaporation, producing a "transparent mist". Garua fog is nearly invisible, yet it still forces drivers to use windshield wipers because of deposition of liquid water on hard surfaces.





Biological effects and human uses
Redwood forests in California receive approximately 30-40% of their moisture from coastal fog. Change in climate patterns could result in relative drought in these areas.[26] Some animals, including insects, depend on wet fog as a principal source of water, particularly in otherwise desert climes, as along many African coastal areas. Some coastal communities use fog nets to extract moisture from the atmosphere where groundwater pumping and rainwater collection are insufficient.

Armies have advanced under fog to hide their movements from the opposing forces.[citation needed]

Artificial fog is man-made fog that is usually created by vaporizing a water and glycol-based or glycerine-based fluid. The fluid is injected into a heated block, and evaporates quickly. The resulting pressure forces the vapor out of the exit. Upon coming into contact with cool outside air, the vapor condenses in microscopic droplets and appears as fog.[27]
 
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Big Daddy

Super User
I live in a cold place, and that is the reason I pointed it out because this thing is not normal. Yes, technically smog is fog (smoke+fog), but don't give any justification that it occurs naturally because it should not at the temperatures in India unless there is a lot of air pollution and especially at the time when these pictures were clicked. Fog vanishes so quickly as soon as sun rays hit it. Bharatpur is industrial town with some Birla companies (e.g., Cimmco) so these guys are polluting air.

I only mentioned it for awareness because most civilized people will fight against such pollution as opposed to justifying it.

I lived in San Francisco area where smog was a problem. They needed smog tests for all cars sold out of state, which I think is a scam because most car repair shop will fail a car and then charge you money. State also gets some fees. California, New York and New Jersey are third world states in the US. Full of dirty, filthy and scammers galore. These states will tax you as if you live in Europe.
 
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citymonk

Super User
Great thread.
Pushpinder ji thanks for linking me here.
Search engine of this site is not very good in terms of finding relevent information. I was searching Bharatpur since long but was never lucky enough to stumble on epic thread like this one.

Availability of cycles is gem of information you have given here.
And only for this reason, I am ready to go there in wrong season.

Btw are cycles for 10 year olds available.
 
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