How does Fog Form?

Question

i need to know everything there is to know about fog its a science fair project...

Answer 1

Dear Emogirl - good question. Fog, which is nothing but a cloud at ground level, forms when the air becomes saturated. It generally forms during the night as the temperature drops. When the temperature reaches the dew point temperature the air is at 100% humidity and fog begins to form. Hope this helps to explaine it for you.

Answer 2

Most types of fog form when the relative humidity reaches 100% at ground-level. Fog can form suddenly, and can dissipate just as rapidly, depending what side of the dewpoint the temperature is on.

An important exception to the general rule is sea fog. This is due to the peculiar effect of salt. 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.

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