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Words begining with "P"
The study of ancient or prehistoric qeoqraphy.
Climate as it existed in the distant past, particularly before
Sensitive to all or most of the visible spectrum.
The addition of one or more redundant bits to information to
verify its accuracy.
Types of parity
- Even Parity - The additional bit added to a 7 bit byte to
ensure that there are an even number of 1's in the byte of
- Odd Parity - The additional bit added to a 7 bit byte to
ensure that there are an odd number of 1's in the byte of
Unit of atmospheric pressure named in honor of Blaise Pascal
(1632-1662), whose experiments greatly increased knowledge of the
atmosphere. A pascal is the force of one newton acting on a surface
area of one square meter. It is the unit of pressure designated by
the International System.
100,000 Pa = 1000 mb = 1 bar See atmospheric
A system sensing only radiation emitted by the object being viewed
or reflected by the object from a source other than the system. See
The instruments that are accommodated on a spacecraft.
Perigee (aka periapsis or perifocus)
On an elliptical orbit path, the point where a satellite is
closest to the Earth. See Keplerian
The point in the orbit of a planet or comet which is nearest the
Sun (as opposed to the aphelion, which is the point in the orbit
farthest from the Sun).
Time required for a satellite to make one complete orbit.
Period Decay (aka Decay)
The tendency of a satellite to lose orbital velocity due to the
influence of atmospheric drag and gravitational forces. A decaying
object eventually impacts the surface of the Earth or burns up in the
atmosphere. This parameter directly affects the satellites mean
Minor corrections to the Keplerian model of a satellite orbit as
an ellipse of constant shape and orientation. Since satellite orbits
are affected by Earth's gravity and drag caused by the Earths
atmosphere (causing satellites to spiral downward), minor adjustments
must be made to the orbit.
A symbol for the degree of acidity of alkalinity of solution.
Expressed as a negative logarithm of the hydrogen ion concentration
in a solution, pH = -log[H+]. If the hydrogen ion
concentration of a solution increases, the pH will decrease, and vice
versa. The value for pure distilled water is regarded as neutral, pH
values from 0 to 7 indicate acidity, and from 7 to 14 indicate
In direct readout, the
time between the end of a satellite image start tone and start of the
actual frame data. The phase interval represents white level video,
interrupted by a black level pulse marking the start of each line and
is used to set up phasing prior to image display.
Subdiscipline of agriculture, a science that treats relations
between climate and periodic biolgical phenomena that are related to
or caused by climate conditions, such as the budding of trees and
migration of birds.
A type of smog that forms in large cities when chemical reactions
take place in the presence of sunlight, its principal component is
ozone. Ozone and other
oxidants are not emitted into the air directly but form from
reactions involving nitrogen oxides and hydrocarbons. Because of its
smog-making ability, ozone in the lower atmosphere
(troposphere) is often referred to as "bad" ozone.
A quantum (smalles unit in which waves may be emitted or absorbed)
Photosynthetically Active Radiation
Electromagnetic radiation in the part of the spectrum used by
plants for photosynthesis.
Physical Climate System
The system of processess tht regulate climate, including
atmospheric and ocean circulation, evaporation
Smallest par (addressable element) of an electronically-coded
image, such as a computer display. Pixel is a contraction of "picture
The fraction of incident solar radiation that is reflected by a
planet and returned to space. The planetary albedo of the
Earth-atmosphere system is approximately 30%, most of which is due to
backscatter from clouds in the atmosphere.
A fourth state of matter (in addition to solid, liquid, and gas)
that exists in space. In this state, atoms are positively charged and
share space with free negatively-charged electrons. Plasma can
conduct electricity and interact strongly with electric and magnetic
fields. The solar wind is actually hot plasma blowing from the sun.
Concept that the Earth's crust is composed of rigid plates that
move over a less rigid interior.
A satellite that can carry instruments. See bus.
The same term is applied to automatic weather data transmitters
installed on bouys, ballons, ships and planes, and mounted in remote
POES (Polar-orbiting Operational Environmental Satellite)
Operated by the National Oceanic and Atmospheric Administration,
they are designated "NOAA
satellites." Included in this group are the current series of
TIROS-N satellites, the
third-generation polar-orbiting environmental spacecraft operated by
An orbit with an orbital inclination
of near 90 degrees where the satellite ground track will cross both
polar regions once during each orbit. The term is used to describe
the near-polar orbits of spacecraft such as the USA's NOAA/TIR0S
and Landsat orbit path satellites.
The comparatively slow torquing of the orbital planes of all
satellites with respect to the Earth's axis, due to the bulge of the
Earth at the equator which distorts the Earths gravitational field.
Precession is manifest by the slow rotation of the line of nodes of
the orbit (westward for inclinations less than 90 degrees and
eastward for inclinations greater than 90 degrees).
Moisture that falls from clouds. Although clouds appear to float
in the sky, they are always falling, their water droplets slowly
being pulled down by gravity. Because their water droplets are so
small and light, it can take 21 days to fall 1,000 feet and wind
currents can easily interrupt their descent. Liquid water falls as
rain or drizzle. All raindrops form around particles of salt or dust.
(Some of this dust comes from tiny meteorites and even the tails of
comets.) Water or ice droplets stick to these particles, then the
drops attract more water and continue getting bigger until they are
large enough to fall out of the cloud. Drizzle drops are smaller than
raindrops. In many clouds, raindrops actually begin as tiny ice
crystals that form when part or all of a cloud is below freezing. As
the ice crystals fall inside the cloud, they may collide with water
droplets that freeze onto them. The ice crystals continue to grow
larger, until large enough to fall from the cloud. They pass through
warm air, melt, and fall as raindrops.
When ice crystals move within a very cold cloud ( 10 dgrees F and
-40 degrees F) and enough water droplets freeze onto the ice
crystals, snow will fall from the cloud. If the surface temperature
is colder than 32 degrees F the flakes will land as snow.
- one raindrop .000008 Ibs
- one snowflake .0000003 Ibs
- one cumulus cloud 10,000,000 Ibs
- one thunderstorm 1 0, 000, 000, 000 Ibs
- one hurricane i 0, 000, 000. 000, 000 Ibs
Winds in the middle latitudes (approximately 30 degrees to 60
degrees) that generally blow from west to east. The subtropical high
pressure regions at the horse
latitudes (30 degrees) forces surface air poleward, and the
rotation of the Earth causes these winds to bear to the right (east)
in the Northern Hemisphere and to the left (east) in the Southern
Hemisphere (see Coriolis
force). This is, to some extent, an idealized picture of the
atmospheric circulation. The actual circulation on individual days
includes modifications and variations due to the migratory cyclones
and anticyclones of middle
latitudes, causing rapid and often violent weather changes, as warm
semi-tropical air from the horse latitudes meets cold polar air from
the high latitudes. See wind.
An imaginary line running from north to south through Greenwich,
England, used as the reference point for longitude.
A fiber card on which integrated circuits and other electronic
components can be mounted. Connections between the components are
etched in the correct circuit patterns.
An association of phenomena governed by physical, chemical, or
biological laws. An example of a process is the vertical mixing of
ocean waters in the so-called surface-mixed layer; the state
variables for this process include temperature, salinity in the water
on a vertical scale of tens of meters, and heat flow and wind stress
at the sea surface. Other examples include the volcanic deposition of
dust and gases into the atmosphere, eddy formation in the atmosphere
and oceans, and soil development.
An organized, systematic investigation of a particular process
designed to identify all of the state variables involved and to
establish the relationships among them. Process studies yield
numerical algorithms that
connect the state variables and determine their rates of change; such
algorithms are essential ingredients of Earth system models.
Orbits of the Earth in the same direction as the rotation of the
An instrument designed to measure dew point and relative humidity,
consisting of two thermometers (one dry bulb and one wet bulb). The
dew point and humidity levels are determined by drying the wet bulb
(either by fanning or whirling the instrument) and comparing the
difference between the wet and dry bulbs with preexisting
calculations. See hygrometer.
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