Subj : Weather Glossary (Z)
To   : All
From : Daryl Stout
Date : Mon May 27 2019 12:14 am

  This weather glossary contains information on more than 2000 terms,
phrases and abbreviations used by the National Weather Service (NWS)...
the government agency who makes weather forecasts, and issues weather
advisories, watches, and warnings, for the United States, and its
territories.

  Many of these terms and abbreviations are used by NWS forecasters to
communicate between each other and have been in use for many years and
before many NWS products were directly available to the public. It is the
purpose of this glossary to aid you in better understanding NWS products.

***

Z
Zulu time; the same as Universal Coordinated Time (UTC), i.e. 18z is the
same as 18:00 UTC.

Zero Datum
In hydrologic terms, a reference "zero" elevation for a stream or river
gage. This "zero" can be referenced (usually within ten feet of the bottom
of the channel) to mean sea level, or to any other recognized datum.

ZFP
Zone Forecast Product

ZL
Freezing Drizzle

ZNS
zones

Zonal Flow
Large-scale atmospheric flow in which the east-west component (i.e.,
latitudinal) is dominant. The accompanying meridional (north-south)
component often is weaker than normal. Compare with meridional flow.

Zone of Aeration
In hydrologic terms, the locus of points just above the water table where
soil pores may either contain air or water. This is also called the
vadose zone.

Zone of Saturation
In hydrologic terms, the locus of points below the water table where
soil pores are filled with water. This is also called the phreatic zone.

Zoned Embankment Dam
In hydrologic terms, an embankment dam which is comprised of zones of
selected materials having different degrees of porosity, permeability
and density.

ZR
Freezing Rain

Zulu (Z) Time
For practical purposes, the same as Coordinated Universal Time (UTC).
The notation formerly used to identify time Greenwich MeanTime. The
word "Zulu" is notation in the phonetic alphabet corresponding to the
letter "Z" assigned to the time zone on the Greenwich Prime Meridian.

Zurich Sunspot Classification
In solar-terrestrial terms, a sunspot classification system that has
been modified for SESC use.

Z\/R Relationship
An empirical relationship between radar reflectivity factor z
(in mm^6 / m^3 ) and rain rate ( in mm / hr ), usually expressed as
Z = A R^b; A and b are empirical constants.
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