Flashcards in Atmospheric Moisture Deck (56)
What is the hydrologic cycle?
The transfer of water from earth to the atmosphere and back again
What are the two types of moisture in the atmosphere?
1. Absolute Humidity
2. Relative Humidity
What is absolute humidity?
Mass of water vapor in a given volume of air; e.g. 20 gr H2O / 1 m3 air
What is relative humidity?
Actual water content of air/ potential amt. water air could hold
What controls the water capacity of an air parcel?
What has a greater capacity to hold water vapor, warmer or cooler air?
Warmer air has a greater capacity to hold water vapor
What is dew?
When condensation occurs directly on a surface
What is dew point?
DEW POINTis the temp at which saturation occurs (RH=100%) and condensation begins, DEW FORMS
What happens if the dew point is less then the freezing point?
water vapor sublimates (gas to solid) as ice crystals = FROST
When does Frost and Dew form and why?
FROSTFrost and Dew form at night (or early morning) due to radiationalcooling:earth radiates heat away and cools
What is Dew Point a clear indicator of?
The water content of the air
If there is a high dew point what does that mean?
If there is a low dew point temperature what does that mean?
What are clouds?
CLOUDS= Condensation forms that develop above the ground
What are two important points to remember about clouds?
1. Condensation does NOT= Precipitation (PPT)
2. Clouds consist of solid or liquidwater… NOT water vapor which is a gas
How are clouds classified?
By height and shape
What are the three main types of cloud I need to know?
What happens when you add nimbus or nimbo to these clouds?
It means that the clouds produce rain.
Examples –nimbostratus, cumulonimbus
What are Cirrus clouds?
Cirrus–highest, wispy, consist of ice crystals
What do Cirrus clouds signal?
Approaching weather (a front)
What are Stratus clouds?
Stratus –horizontal (layer) clouds that form a continuous sheet near the surface(altostratus would be mid-level)
What are Cumulus clouds?
Cumulus–“fair weather cumulus”puffy clouds, show vertical development( indicating convection)–Known by flat bases, distinct outlines
What do towering cumulus clouds indicate>
Towering cumulus clouds indicate intense convection! Much larger, more vertical development than fair weather cumulus
What is fog?
FOG = “cloud on the ground”. Thick layer of moist air cooled to its dew point
What are the 5 types of fog?
What is advection fog?
Involves horizontal movementof air warm air moves over cold surface, is chilled to dew point
Where is advection fog found?
West coast, often involves coastal setting
What is radiation fog?
Radiational cooling of ground surface, chills moist air and condensation occurs, usually pre-dawn hours under H-press. It is stationary rather than moving and always touching ground
Where is radiation fog found?
In most of the world!