Ablation

The atmospheric deterioration of the lens surface of a weapon’s sensors.

Absorptivity

The ratio of absorbed radiation by an object to the absorbed radiation by a black body at the same wavelength and temperature.

Actiniform clouds

Skeletal remains of closed-cell stratocumulus, easily confused with open-cell cumulus.

Air interdiction (AI)

Strikes against enemy targets far behind forward edge of the battle area (FEBA) or forward line of own troops (FLOT).

Airlight

The light that is scattered into the sensor, also called path radiance.

Albedo

The percentage of incident energy actually reflected.

Algorithm

A procedure for solving a mathematical problem. Basically, it is a formula.

Anomalous cloud lines

Low-level stratocumulus cloud line produced by the interaction of ship exhaust with a stable, moist marine air layer forming in regions of light anticyclonic wind flow.

Anvil cirrus

Thunderstorm blowoff.

Apparent contrast

The contrast measured or perceived at some distance from the target.

Arc clouds

A curved line of cumulus clouds formed due to a thunderstorm downdraft of cold dry air.

Attenuation

Any loss of energy due to absorption and scattering of IR radiation by atmospheric elements.

Axis of contraction

The axis of most rapid shrinking where air parcels are moving toward the col.

Axis of dilatation

The axis of most rapid stretching where air parcels are traveling away from the col.

Baroclinic leaf

Thick mid- and upper-level cloud pattern recognized as the first sign of comma-cloud development. It normally has a shallow "S" shape on the sharp upstream edge of the cloud system.

Baroclinic zone cloud system

Multilayered clouds associated with the cold and warm fronts.

Battlefield induced contaminants (BIC)

Contaminants, such as smoke from burning targets and dust raised by bomb impacts, that hide the target scene.

Beam scintillation

Microscale turbulent eddies much smaller than beam width that cause fluctuations of energy intensity within the cross-section of the beam. It does not bend the beam from a straight line of sight or alter the width of the beam.

Beam spread

Microscale eddies, smaller than or about the same size as the beam width, which increase the cross-sectional area of the beam and decrease the intensity of its energy.

Beam wander

Microscale eddies, larger than the beam width, which cause the beam to deviate from a straight line path, thus making aiming more difficult.

Billow clouds

Regularly spaced parallel cirrus cloud bands caused by vertical shear due to the stronger winds aloft, oriented perpendicular to the winds.

Black body

A theoretically perfect absorber and emitter of radiation.

Brightness temperature

The temperature an object/surface appears to have when measuring the intensity of its emitted radiation at a particular frequency/wavelength.

Cirrus streaks

Small isolated patches of cirrus generally occurring away from other clouds and aligned with the upper-level winds.

Close air support (CAS)

Air support of friendly ground forces in close proximity to or engaged with enemy forces along the forward edge of the battle area (FEBA).

Closed-cell stratocumulus

Cellular, closely packed stratocumulus that forms mostly over ocean areas. Forms with rising air in the center of closely packed cloud cells and with descending air at the edges.

Cloud element

The smallest cloud that can be seen on an image as determined by the resolution of the METSAT sensor.

Cloud fingers

Low-level clouds that develop because of low-level convergence.

Cloud lines

A nearly continuous cloud formation where elements are connected and the line is less than one degree in width.

Cloud plumes

Long, narrow stratocumulus lines produced by the turbulent vertical motion of air forced around an island in a strong low-level wind.

Cloud streets

A nearly continuous cloud formation where elements are not connected.

Cloud type

A form of cloud seen in the sky (cumulus, altocumulus, etc.).

Col

The center of the deformation zone where winds are calm.

Comma head

The northern portion of the comma cloud.

Condensation trails

See contrails.

Contamination

Energy sensed by the satellite from two or more sources along the same line of sight.

Contrails

Cirrus cloud lines formed from jet exhaust that appear as unnatural anomalous cloud lines.

Contrast

The difference in reflectance or albedo between an object and its background.

Crossover times

These occur two times during the day when the temperatures of a target and its background are the same. These times occur just after dawn and usually near sunset.

Cut off lows

Small, deep pools of cold air located equatorward of the PFJ.

Deformation

The stretching or shearing of the wind field.

Dendritic

Vein-like.

Diffuse reflector

Occurs when light is reflected equally in all directions, but with diffuse energy.

Divergence

The spreading or contracting of the wind field.

Dry slot

See surge region.

Emissivity

The ratio of emitted radiation from an object to the emitted radiation from a black body at the same frequency (or wavelength) and temperature.

Enhanced cumulus

An area of towering cumulus and small cumulonimbus clouds found in an area of open-cell cumulus due to a secondary vorticity maxima or positive vorticity advection.

Enhancement

A series of gray shades corresponding to thermal values that provide a thermal contrast to features on the imagery.

Foreshortening

A loss of resolution caused by an oblique (shallow) viewing angle that results in a distortion near the edge of the picture on any type of METSAT imagery.

Geometric scattering

Scattering by cloud or fog droplets and precipitation.

Infrared contrast

A radiometric temperature difference between a target and its background.

Inherent contrast

The actual contrast between two objects based solely on their properties.

Integrated water vapor (WV) content

This EDR is a measurement of the amount of water vapor in a column extending from the top of the atmosphere to the surface along the sensor-to-ground path.

Karman vortices

Counter-rotating cloud spirals (eddies) of stratocumulus clouds found in the wake of an island and associated with winds of 10 to 25 knots.

Kirchoff’s law

This law says for objects in thermodynamic equilibrium (a steady temperature), absorption of radiant energy must be equal to the emission of radiant energy.

Land surface temperature (ST)

An estimate of the actual ground temperature.

Launch envelope

The range of altitudes and distances within which a weapon can effectively reach the target without exposing the aircraft to enemy air defenses.

Lee-of-the-mountain cirrus

Multilayered cirrus cloud shield on the lee of a mountain chain.

Leeside cirrus

See lee-of-the-mountain cirrus.

Lithometeors

Dry, solid particles either suspended in the air or lifted from the ground by the wind.

Mesoscale convective complex (MCC)

Organized, persistent areas of deep convection noted in METSAT imagery during the warm season, especially over the US

Moisture channel

See water vapor imagery.

Neutral point

See col.

Oceanic total precipitable water

See integrated water vapor (WV) content.

Offensive counter air (OCA)

Strike missions against enemy airfields, including aircraft on the ground, hardened shelters, and control and support facilities.

Open-cell cumulus

Cumulus clouds that usually form over water behind mid-latitude cyclones. They are caused by strong cold-air advection over warmer water.

Optical turbulence

An atmospheric phenomenon that degrades weapons system performance.

Path radiation

The scattering of light or radiation into your line of sight. Also called airlight.

Planck’s law

This law says the amount of radiation emitted by a black body at a given wavelength is proportional to its temperature.

Polarization

The orientation of the electric and magnetic components of electromagnetic radiation waves.

Polarization difference

The arithmetic difference in temperature between the horizontal and vertical channels at any one frequency.

Precision-guided munition

When an EO sensor is mounted on a bomb or missile itself.

Radiative temperature

The temperature that an object appears to have based on the amount of energy it emits.

Reflectivity

The ratio of the total amount of radiation reflected from the object to the total amount of incident radiation.

Resolution

The smallest individual element a sensor can detect.

Rope clouds

A very narrow line of cumulus/towering cumulus that is usually found over water and, occasionally, over very moist coastal land areas ranging from several hundred miles in length to several thousand.

Rotation

Turning about a point.

Scattering

The redirection of photons by molecules, aerosols, or other particles in the air.

Sea-ice concentration (IC)

A fraction of ocean area covered by ice.

Ship trails

See anomalous cloud lines.

Soil moisture (SM)

A measure of the approximate amount of recently deposited precipitation in the soil.

The Stefan-Boltzmann law

This law relates the total amount of energy emitted at all wavelengths of the EM spectrum to the temperature of the black body.

Stratocumulus lines

SC elements formed by low-level instability caused by a large air/sea temperature difference.

Sun glint

The reflection of the sun’s rays off the water surface directly into the METSAT sensor (seen only on visual imagery).

Suppression of enemy air defenses (SEAD)

These are strike missions against air defenses, including antiaircraft artillery (AAA), surface-to-air missile (SAM) batteries, and ground control intercept radar (GCI) positions.

Surge region

The dry intrusion of air into the comma located near the region of highest winds near the cloud-top level (excluding convective activity).

Target acquisition system

An EO sensor mounted on an aircraft.

Terminator

The transition line from day to night. Only seen on visual imagery.

Thermal capacity

A measure of the amount of heat an object holds.

Thermal clutter

Occurs when some target scenes may be filled with multiple hot and cold objects, making detection of the target difficult.

Thermal conductivity

A measure of how rapidly heat travels through an object.

Thermal contrast

The difference between the thermal energy of the target and that of the background.

Thermal crossover

The moment when the target and the background are at the same temperature.

Threshold contrast

The minimum contrast that your eyes can detect.

Translation

Movement in a straight line.

Transmissivity

The ratio of energy that passes through an object to the total amount of energy received.

Transverse bands

Irregularly spaced, parallel bands of thin cirrus filaments and strands oriented perpendicular to the wind flow.

Triboelectrification

Electric charge buildup.

Vorticity comma-cloud system

Low to mid-level cloudiness in a comma shape. Associated with a vorticity maximum.

Water vapor imagery

Imagery measuring the earth’s radiation at 6.7µm on GOES imagery and 5.7 to 7.1µm on METEOSAT imagery.

Wien’s law

Also called Wien’s displacement law. This law says the wavelength of the maximum irradiance of a black body depends on its temperature.