Chapter 5 - Condensation Flashcards
How can fog form when the relative humidity is less than 100 percent?
Hydroscopic condensation nuclei seek out water and vapor condenses even with low RH; enough of these particles can lead to fog.
Name and describe four types of fog.
1) advection: moist, warm air moves over cold surface, temp. lowers to the dew point
2) radiation: ground fog due to ground cooling making air saturated and condense
3) Upslope: flows up a hill or mountain
4) evaporation: 2 unsaturated masses mix with each other; moist and low temp.
How does evaporation (mixing) fog form?
when two unsaturated air parcels mix and becomes saturated. ex: cold wind over warm water.
Why are advection fogs rare over tropical water?
Advection fog is produced by cooling surface to its saturation point. The surface must be sufficiently cooler than the above air. Tropical waters are warm and are so big that they can not be cooled that much so that the above air is sufficiently warmer.
Explain why steam fog is more likely to form during autumn, and advection fog in early spring, near the shore of an extremely large lake.
During autumn the lake is warmer than the air, hence when the cold wind blows over the lake steam fog is produced. During spring the lake is colder than the air, hence creating advection fog.
Why can you see your breath on a cold morning? Does the air temperature have to be below freezing for this to occur?
Because the mixing of the air and the breath creates a relative humidity above 100%. The air temperature does not have to be below freezing.
