Condensation, Dew, and Fog - Vocabulary Flashcards

Vocabulary flashcards covering condensation, dew point, frost point, condensation nuclei, fog types, haze types, and related processes.

Condensation

The process by which water vapor changes to liquid when air is cooled to its dew point, forming dew, fog, or clouds.

Dew point temperature (Td)

The temperature at which air becomes saturated and water vapor begins to condense.

Frost point

The temperature Td below 32°F at which frost forms instead of dew.

Condensation nuclei (CCN)

Tiny particles in the air that water vapor condenses onto; sources include dust, volcanoes, smoke, forest fires, sea salt, and sulfate from phytoplankton.

Hygroscopic CCN

CCN that readily condense water because they attract moisture (e.g., sea salt).

Hydrophobic CCN

CCN that do not readily condense water (water-repellent particles like wax).

Dry haze

Haze formed by large/giant particles (smoke, smog, dust); often appears redder.

Wet haze

Haze formed when water condenses on hygroscopic CCN but does not grow large; appears dull gray.

Fog

A cloud at ground level formed when relative humidity approaches 100%; visibility is reduced.

Radiation fog

Fog formed by radiational cooling on clear, calm nights; often valley fog; forms when air near surface cools to the dew point.

Advection fog

Fog formed when warm, moist air moves over a cooler surface and cools to the dew point; requires a light breeze; common on west coasts.

Upslope fog

Fog formed as air is forced up a slope, expands, and cools to the dew point; requires wind and a slope.

Steam fog

Fog over warm water when cold air moves over it; unstable layering with warm surface air rising.

Mixing fog

Super-saturation occurs when two saturated air parcels at different temperatures mix; saturation is not linear with temperature.

Adiabatic expansion

Cooling of an air parcel as it expands when rising; expansion cools, compression warms; no heat transfer with surroundings.

Valley fog

Radiation fog that forms in valleys where cold air pools at the bottom.

Total CCN mass annually

Approximately 2 × 10^12 kilograms of condensation nuclei are introduced into the atmosphere each year.

Fog forecast impacts

Fog can significantly affect aviation, ground transportation, and maritime activities due to reduced visibility.