INFERIOR MIRAGEA spurious image of an
object formed below the true position of that object
by abnormal refractive conditions along the line of
sight; one of the most common of all types of
mirage, and the opposite of a superior mirage.
INSOLATION(contracted from incoming solar
radiation) In general, solar radiation received at
INSTABILITYA property of the steady state of a
perturbations introduced into the steady state will
increase in magnitude, the maximum perturbation
amplitude always remaining larger than the initial
INSTABILITY LINEAny non-frontal line or band
of convective activity in the atmosphere.
INVERSIONThe departure from the usual decrease
or increase with altitude of the value of an
atmospheric property. The layer through which this
departure occurs is known as the inversion layer,
and the lowest altitude at which the departure is
found is known as the base of the inversion. The
term is almost always used in reference to
temperature, but may be applied to moisture and
KATABATIC WINDAny wind blowing down an
incline; the opposite of anabatic wind. If the wind
is warm, it is called a foehn; if cold, it may be a fall
or gravity wind.
KINETIC ENERGYThe energy that a body
possesses as a consequence of its motion, defined
as the product of one-half of its mass and the square
of its speed, 1/2mv squared.
LAND BREEZEA coastal breeze blowing from
land to sea, caused by the temperature difference
when the sea surface is warmer than the adjacent
LAPSE RATEThe decrease of an atmospheric
temperature, unless otherwise specified.
LATERAL MIRAGEA very rare type of mirage in
which the apparent position of an object appears
displaced to one side of its true position.
LIGHTVisible radiation (about 0.4 to 0.7 micron in
wavelength) considered in terms of its luminous
atmosphere, thus permitting objects to be seen that
are usually below the horizon.
LOWAn area of low pressure, refer-ring to a
dimensions (closed isobars) on a constant-height
chart or a minimum of height (closed contours) on
a constant-pressure chart. Lows are associated with
cyclonic circulations, and the term is used
interchangeably with cyclone.
MACROCLIMATEThe general large-scale climate
of a large area or country, as distinguished from the
mesoclimate and microclimate.
MAGNETIC NORTHAt any point on Earths
surface, the horizontal direction of the Earths
magnetic lines of force (direction of a magnetic
meridian) toward the north magnetic pole, i.e., a
direction indicated by the needle of a magnetic
compass. Because of the wide use of the magnetic
compass, magnetic north, rather than TRUE
NORTH, is the common 0° (or 360°) reference in
much of navigational practice, including the
designation of airport runway alignment.
characteristics are developed over an extensive
water surface and which, therefore, has the basic
maritime quality of high moisture content in at least
it's lower levels.
MEAN SEA LEVELThe average height of the sea
surface, based upon hourly observation of tide
height on the open coast or in adjacent waters
which have free access to the sea. In the United
States, mean sea level is defined as the average
height of the surface of the sea for all stages of the
tide over a 19-year period.
MESOCLIMATEThe climate of small areas of
Earths surface that may not be representative of the
considered in mesoclimatology include small
valleys, frost hollows, forest clearings, and open
spaces in towns, all of which may have extremes of
temperature differing by many degrees from those
of adjacent areas. The mesoclimate is intermediate
MESOPAUSEThe top of the mesosphere.
corresponds to the level of minimum temperature at
70 to 80 km.