Subj : Wx Terms (A)(1)
To : All
From : Daryl Stout
Date : Sun Sep 03 2017 10:39 am
A
1. Abbrevation for hail in weather observations.
2. Symbol used on long-term climate outlooks issued by CPC to indicate
areas that are likely to be above normal for the specified parameter
(temperature, precipitation, etc.).
A AMS
Arctic Air Mass
A Index
A daily index of geomagnetic activity derived as the average of the eight
3-hourly a indices.
AAAS
American Association for the Advancement of Science
AAWU
Alaskan Aviation Weather Unit
Ablation
Depletion of snow and ice by melting and evaporation.
ABNDT
Abundant
Absolutely Stable Air
An atmospheric condition that exists when the environmental lapse rate
is less than the moist adiabatic lapse rate.
Absolutely Unstable Air
An atmospheric condition that exists when the environmental lapse rate
is greater than the dry adiabatic lapse rate.
Absorption
The process in which incident radiant energy is retained by a substance
by conversion to some other form of energy.
ABT
About
Abutment
The part of a valley or canyon wall against which a dam is constructed.
Right and left abutments are those on respective sides of an observer
looking downstream.
Abutment Seeping
Reservoir water that moves through seams or pores in the natural abutment
material and exits as seepage.
ABV
Above
AC
1. Abbreviation for Altocumulus - a cloud of a class characterized by
globular masses or rolls in layers or patches, the individual elements
being larger and darker than those of cirrocumulus and smaller than those
of stratocumulus. These clouds are of medium altitude, about 8000-20,000
ft (2400-6100 m).
2. Convective outlook issued by the Storm Prediction Center. Abbreviation
for Anticipated Convection; the term originates from the header coding
[ACUS1] of the transmitted product.
ACCAS
(usually pronounced ACK-kis) - AltoCumulus CAStellanus; mid-level clouds
(bases generally 8 to 15 thousand feet), of which at least a fraction of
their upper parts show cumulus-type development. These clouds often are
taller than they are wide, giving them a turret-shaped appearance. ACCAS
clouds are a sign of instability aloft, and may precede the rapid
development of thunderstorms.
Accessory Cloud
A cloud which is dependent on a larger cloud system for development and
continuance. Roll clouds, shelf clouds, and wall clouds are examples of
accessory clouds.
Accretion
The growth of a precipitation particle by the collision of a frozen
particle with a supercooled liquid water droplet which freezes upon
impact.
ACCUMS
accumulation
Accuracy
Degree of conformity of a measure to a standard or true value; in other
words, how close a predicted or measured value is to the true value.
Acid Precipitation
Precipitation, such as rain, snow or sleet, containing relatively high
concentrations of acid-forming chemicals that have been released into the
atmosphere and combined with water vapor; harmful to the environment.
Acid Rain
Rain containing relatively high concentrations of acid-forming chemicals
that have been released into the atmosphere and combined with water vapor;
harmful to the environment.
ACLD
Above Cloud Level
ACPY
Accompany
Acre-foot
The amount of water required to cover one acre to a depth of one foot.
An acre-foot equals 326,851 gallons, or 43,560 cubic feet.
ACRS
Across
Action Stage
The stage which, when reached by a rising stream, represents the level
where the NWS or a partner/user needs to take some type of mitigation
action in preparation for possible significant hydrologic activity. The
appropriate action is usually defined in a weather forecast office (WFO)
hydrologic services manual. Action stage can be the same as forecast
issuance stage.
Active
(abbrev. ACTV). In solar-terrestrial terms, solar activity levels with at
least one geophysical event or several larger radio events (10cm) per day
(Class M Flares).
Active Conservation Storage
In hydrologic terms, the portion of water stored in a reservoir that can
be released for all useful purposes such as municipal water supply, power,
irrigation, recreation, fish, wildlife, etc. Conservation storage is the
volume of water stored between the inactive pool elevation and flood
control stage.
Active Dark Filament (ADF)
In solar-terrestrial terms, an Active Prominence seen on the Disk.
Active Longitude
In solar-terrestrial terms, the approximate center of a range of
heliographic longitudes in which Active Regions are more numerous and
more flare-active than the average.
Active Prominence
In solar-terrestrial terms, a prominence displaying material motion and
changes in appearance over a few minutes of time.
Active Prominence Region (APR)
In solar-terrestrial terms, a portion of the solar limb displaying active
prominences.
Active Region (AR)
In solar-terrestrial terms, a localized, transient volume of the solar
atmosphere in which plages, sunspots, faculae, flares, etc. may be
observed.
Active Storage Capacity
In hydrologic terms, the total amount of reservoir capacity normally
available for release from a reservoir below the maximum storage level.
It is total or reservoir capacity minus inactive storage capacity. More
specifically, it is the volume of water between the outlet works and the
spillway crest.
Active Surge Region (ASR)
In solar-terrestrial terms, an Active Region that exhibits a group or
series of spike-like surges that rise above the limb.
ACTV
Active. In solar-terrestrial terms, solar activity levels with at least
one geophysical event or several larger radio events (10cm) per day
(Class M Flares)
ACYC
Anticyclone - A large-scale circulation of winds around a central region
of high atmospheric pressure, clockwise in the Northern Hemisphere,
counterclockwise in the Southern Hemisphere.
Additive Data
A group of coded remarks that includes pressure tendency, amount of
precipitation, and maximum/minimum temperature during specified periods
of time.
ADDS
Aviation Digital Data Service
Adiabat
A line on a thermodynamic chart relating the pressure and temperature of
a substance (such as air) that is undergoing a transformation in which
no heat is exchanged with its environment.
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