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atmospheric entry
Air/Earth current continuously degrades ***, believed
that thunderstorms reinforce it.
atmospheric entry Re-entry, or entry of extraterrestrial
bodies such as meteors.
atmospheric filtering Use of upper zones of ionosphere
and mesosphere to filter out ICBM decoys from true
warheads, it being supposed that latter will have higher
density, better thermal protection and increasingly
divergent trajectories, while decoys decelerate more
violently, fall behind and burn up.
atmospheric pressure See atmosphere (4), atmospheric
regions.
atmospheric refraction Bending of EM radiation as it
passes through different layers of atmosphere, esp.
obliquely. Affects radio and radar, esp. when directionally
beamed; visibly manifest in air over, say, hot roadway
in sunshine when objects seen through this air ‘shimmer’;
in astronavigation ** makes apparent altitude of celestial
bodies falsely great.
atmospheric regions Layers of Earth’s atmosphere differ
in different model atmospheres; following notes are based
on ISA. Lowest layer, troposphere, extends from SL to
about 8 km (26,000 ft) at poles, to 11 km (36,090 ft) in
temperate latitudes, and to 16 km (52,000 ft) over tropics.
Throughout this region ISA characteristics of temperature,
pressure and relative density are precisely plotted.
Assumed lapse rate is 6.5°C km –1 and at tropopause,
taken in ISA to be 11 km (36,090 ft), temperature is
–56.5°C. From tropopause stratosphere extends at almost
constant temperature but falling pressure to 30 km,
stratopause, above which is mesosphere. Here there is
reversed lapse rate, temperature reaching peak of about
10°C at 47.35–52.43 km, thereafter falling again to
minimum of 180.65°K at mesopause (79.994–90.000 km).
Above this is ionosphere, extending to at least 1,000 km,
where temperature again rises through 0°C (273°K) at
about 112 km and continues to over 1,000°C at 150 km
and to peak of about 1,781°C at 700 km. Between
100–150 km lies E (Kennelly-Heaviside) layer; at
200–400 km is F (Appleton) layer, which at night is single
band but by day divides into F1 and F2, F2 climbing to
400–500 km on summer day. E and F layers are reflective
to suitable EM radiation striking at acute angle. Above
ionosphere is open-topped exosphere, from which atmospheric
molecules can escape to space and where mean free
path varies with direction, being greatest vertically
upward. Other ** are based upon composition, electrical
properties and other variables.
atmospheric tides Produced by gravitational attraction
of Sun and Moon. Latter exerts small influence, equal to
equatorial pressure difference of 0.06 mb, but solar ** has
12 h harmonic component (apparently partly thermal) of
1.5 mb in tropics and 0.5 in mid-latitudes.
atmospheric turbulence See gust, CAT.
ATMRP Air traffic management research
program[me].
ATMS 1 Air-traffic management system[s].
2 Advanced-technology microwave sounder.
ATN 1 Aeronautical telecommunications network.
2 Air-traffic network.
Atnavics Air-traffic navigation integration and coordination
system (USA).
ATNM Air-traffic network management.
ATNP ATN(1) panel.
ATR
ATNS Air-traffic [and] navigation services.
ATO 1 Air task, or tasking, order.
2 Assisted takeoff.
3 Abandoned takeoff.
4 Abort to orbit, ie cannot avoid making a complete
orbit.
5 Airborne tactical officer.
6 Auto [reporting of] time over[head].
7 Authorization, or authority, to offer.
8 Air Traffic Organization (FAA, November 2003–).
ATOA Air Taxi Operators Association (UK).
Atoc(s) Allied tactical operations centre(s) (NATO).
A to F Authority to fly.
ATOL 1 Air travel organiser’s (or operator’s) licence
(UK, a major function is to protect passenger after bankruptcy
of carrier).
2 See ATOLS.
Atol Advanced trainer on localizer.
Atoll Assembly/test oriented launch language.
ATOLS Automatic takeoff and landing system (UAV).
ATOM Aileron trim offset monitor.
atom bomb Colloq., fission bomb; very loosely, any NW
(see nuclear weapon).
atomic materialization Growth of thin-film coating by
bombardment with ions and clusters [IR stealth].
atomic number Symbol Z, number of protons in atomic
nucleus or number of units of positive electronic charge it
bears.
atomic weight Mass of atom of element in units each
1/12th that of atom of carbon 12 (refined to 12.01115 on
1961 table). Numerical value for each element is same as
atomic mass.
atomising Continuous conversion of solid or liquid, esp.
high-pressure jet of liquid, into spray of fine particles.
Also called atomisation.
ATOP 1 Airline training orientation program (US).
2 Advanced Technology [or Technologies] and Oceanic
Procedures (FAA), Lockheed Martin).
Atops Advanced transport operating systems (NASA).
ATOS 1 Automated technical-orders system.
2 Air Transportation Oversight System (FAA).
ATP 1 At time, place.
2 Actual track pointer.
3 Authority, or authorization, to proceed.
4 Aviation technical regiment (USSR).
5 Application transaction program (SNA).
6 Airborne [USAF, Advanced] targeting pod.
7 Air-transport pilot [ALTP is preferred].
8 Advanced tow placement, manufacturing process
for precise composite structure.
9 Air-turbine pump.
10 Allied technical publication.
11 Attack plot.
12 Acceptance-test procedure.
13 Aeronautics Test Program (NASA).
ATPAC Air-Traffic Procedures Advisory Committee
(US).
ATPCS Automatic takeoff power control system.
ATPI Air Travel Price Index (BTS).
ATPL Airline [or air] transport pilot’s licence; ALTP
licence; /H adds endorsement for helicopters [required to
be PIC of civil aircraft 20,000 kg MTOW].
ATR Air, or airline, transport radio, Arinc system of
standardizing dimensions of airborne electronics boxes,
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