chromonema(pl.: chromonemata) An optically single thread forming an axial structure within each chromosome.
chromoplastPlastid containing pigments other than chlorophyll. See: chloroplast.
chromosomal aberrationAn abnormal change in chromosome structure or number, including deficiency, duplication, inversion, translocation, aneuploidy, polyploidy, or any other…
chromosomal integration siteA chromosomal location where foreign DNA can be integrated, often without impairing any essential function in the host organism.
Chromosomal inversionChromosome segments that have been turned 180 degrees. The gene sequence for the segment is reversed with respect to the rest of the chromosome.
chromosomal polymorphismThe occurrence of one to several chromosomes in two or more alteRNA tive structural forms within a population; the structurally changed chromosomes are…
Chromosome(KROH-muh-some) Part of a cell that contains genetic information. Except for sperm and eggs, all human cells contain 46 chromosomes.
chromosome bandingDifferential staining of chromosomes in such a way that light and dark areas occur along the length of the chromosomes in repeatable patterns.
chromosome jumpingA technique that allows two segments of duplex DNA that are separated by thousands of base pairs (about 200 kb) to be cloned together.
chromosome landingAn alteRNA tive to chromosome walking for positional cloning. Clones of genomic DNA are fragmented so as to include both the target gene and a closely…
chromosome mutationA change in the gross structure of a chromosome, usually causing severely deleterious effects in the organism, but can be maintained in a population (See…
Chromosome paintingAttachment of certain fluorescent dyes to targeted parts of the chromosome. Used as a diagnositic for particular diseases, e.g. types of leukemia.
chromosome theory of inheritanceThe theory that chromosomes carry the genetic information and that their behaviour during meiosis provides the physical basis for segregation and…
Chromosome walkingWorking from a flanking DNA marker, overlapping clones are successively identified that span a chromosomal region of interest. (See Chromosome.)
ChromosomesThe self-replicating genetic structure of cells containing the cellular DNA. Humans have 23 pairs of chromosomes.
Chromosphere2,500 km thick (1,600 mi) layer of plasma above the Sun’s photosphere. Temperatures range from ~4500 K to 60,000 K (110,000 to 8,000°F).
Chromospheric EventsIn solar-terrestrial terms, flares that are just Chromospheric Events without Centimetric Bursts or Ionospheric Effects. (SID) (Class C flare)
Chronic effectsEffects resulting from exposure to low levels of a stressing factor (e.g., contaminant, disease, electromagnetic field, noise, and radionuclides) over…
chronologya general term for the age-depth relationship in ice, sediment, or another deposit.
chymosinAn enzyme that clots milk, used in the manufacture of cheese.
CICirrus clouds- High-level clouds (16,000 feet or higher), composed of ice crystals and appearing in the form of white, delicate filaments or white or…
CienegaA perennially wet area supported by a spring or other water source; also called wetland, marsh, or swamp.
CIGCeiling- The height of the lowest layer of clouds, when the sky is broken or overcast.
cilium(pl.: cilia) Hairlike locomotor structure on certain cells; a locomotor structure on a ciliate protozoan.
CINGrowth of abnormal cells on the surface of the cervix. Numbers from 1 to 3 may be used to describe how abnormal the cells are and how much of the cervical…
Cinder coneA conical hill formed around a volcanic vent by the accumulation of loose cinders and other pyroclastics ejected during a volcanic eruption, normally…
Cipolletti weir (trapezoidal weir)A contracted weir of trapezoidal shape in which the sides of the notch are given a slope of 1 horizontal to 4 vertical.
circadianOf physiological activity, etc.: recurring at approximately 24-hour intervals.
Circle of influenceThe circular outer edge of a depression produced in the water table by the pumping of water from a well. See cone of influence.
CircuitA device, or system of devices, that allows electrical current to flow through it and allows voltage to occur across positive and negative terminals.
Circuit breakerAfter the stock market crash of 1987, stock and commodities exchanges established a system of trigger-point rules known as circuit breakers.
Circuit LagAs time increases from zero at the terminals of an inductor, the voltage comes to a particular value on the sine function curve ahead of the current.
Circuit mileFor single circuit electric power transmission lines, circuit miles are equal to geographic miles or pole miles.
circularizationThe self-ligation of a linear DNA fragment having complementary ends, generally generated by digestion with a restriction endonuclease.
Circulating Fluidized BedA type of furnace or reactor in which the emission of sulfur compounds is lowered by the addition of crushed limestone in the fluidized bed thus obviating…
Circulation(ser-kyoo-LAY-shun) In the body, the flow of blood through the heart and blood vessels, and the flow of lymph through the lymph vessels.
Circumpolar vortexCircumpolar vortex The large-scale cyclonic circulation in the middle and upper troposphere centered generally in the polar region.
CirqueBowl-like depression carved into a mountaintop by ice at the head of a glacier.
CirriformHigh altitude ice clouds with a very thin wispy appearance.
CirrocumulusA cirriform cloud characterized by thin, white patches, each of which is composed of very small granules or ripples.
CirrostratusA cloud of a class characterized by a composition of ice crystals and often by the production of halo phenomena and appearing as a whitish and usually…
Cirrus(abbrev. CI) High-level clouds (16,000 feet or higher), composed of ice crystals and appearing in the form of white, delicate filaments or white or mostly…
cis heterozygoteA double heterozygote that contains two mutations arranged in a cis configuration (e.g. a+ b+ / a b).
cis-acting proteinA protein with the particular property of acting only on the molecule of DNA from which it was expressed.
cis-acting sequenceA nucleotide sequence that only affects the expression of genes located on the same chromosome.
CisternA small tank (usually covered) or a storage facility used to store water for a home or farm. Often used to store rain water.
CistronA DNA sequence that codes for a specific polypeptide; a gene. See DNA, Gene.
City GateGenerally refers to the location at which gas changes ownership or transportation responsibility from a pipeline to a local distribution company or gas…
Civil DawnThe time of morning at which the sun is 6 degrees below the horizon. At this time, there is enough light for objects to be distiguishable and that outdoor…
Civil Defense AgencyState and/or local agency responsible for emergency operations, planning, mitigation, preparedness, response, and recovery for all hazards.
Civil DuskThe time at which the sun is 6 degrees below the horizon in the evening. At this time objects are distinguishable but there is no longer enough light to…
Civil Emergency Message(Abbrev. CEM) - A message issued by the National Weather Service in coordination with Federal, state or local government to warn the general public of a…
CLAn abbreviation used on climate outlook maps issued by CPC to indicate areas where equal chances of experiencing below-normal, normal, and above-normal…
Clam shell gateHigh pressure regulating gate consisting of two curved leaves which open and close over the end of a conduit.
ClarifierA tank used to remove solids by gravity, to remove colloidal solids by coagulation, and to remove floating oil and scum through skimming.
Class (pipe and fittings)The working pressure rating of a specific pipe for use in water distribution systems which includes allowances for surges.
Class I AreaAny area designated for the most stringent protection from air quality degradation.
Class I AreasGeographic areas designated by the Clean Air Act where only a small amount or increment of air quality deterioration is permissible.
Class II AreaAny area where air is cleaner than required by federal air quality standards and designated for a moderate degree of protection from air quality…
Class IVAll other intermittent streams not meeting higher class criteria.
class switchingThe process during which a plasma cell stops producing antibodies of one class and begins producing antibodies of another class.
ClayA very fine-grained rock or mineral fragment of any composition that has a diameter of less than 0.002 mm.
Clay sizeThat portion of the soil finer than 0.002 mm (0.005 mm in some cases).
CLDCloud- A visible aggregate of minute water droplets or ice particles in the atmosphere above the Earth's surface.
Clean Air Act (CAA)(CAA)The Superfund law incorporates those substances listed as hazardous air pollutants under section 112 of the Clean Air Act (CAA) as CERCLA hazardous…
Clean Air Act Amendments of 1990Amendments to the Clean Air Act of 1970 creating two gasoline standards to reduce vehicle emissions in highly polluted cities by requiring gasoline to…
Clean Power GeneratorA company or other organizational unit that produces electricity from sources that are thought to be environmentally cleaner than traditional sources.
Clean Water ActSee Federal Water Pollution Control Act of 1948.
Clean Water Act (CWA)(CWA)The Superfund law incorporates those substances listed as hazardous water pollutants under section 311 (b)(4) of the Clean Water Act (CWA) as CERCLA…
Clear Air Turbulence(CAT) - In aviation, sudden severe turbulence occurring in cloudless regions that causes violent buffeting of aircraft.
Clear IceA thin coating of ice on terrestrial objects, caused by rain that freezes on impact.
Clear SlotWith respect to severe thunderstorms, a local region of clearing skies or reduced cloud cover, indicating an intrusion of drier air; often seen as a…
Clear_skyClear sky Sky with a total cloud cover of less than one okta (or one-tenth in the United States).
ClearanceClearance is the first half of the process that completes your order to buy or sell a security.
ClearcutThe removal, in a single cutting, of the entire stand of trees within a designated area.
ClearingThe registration and settlement of a trade that includes provisions for margin requirement and performance guarantee.
Clearing and grubbingCleaning a site to prepare it for construction. Involves removing debris, structures, shrubbery, trees, obstructions, and objectionable and unsuitable…
CleavageThe process of cell division in the very early embryo before it becomes a blastocyst.
cleaveTo break phosphodiester bonds of double-stranded DNA, usually with a type II restriction endonuclease. Synonyms: cut; digest.
cleaved amplified polymorphic sequenceA segment of DNA that can be amplified by polymerase chain reaction (PCR) and which contains a DNA sequence polymorphism.
ClerestoryA window located high in a wall near the eaves that allows daylight into a building interior, and may be used for ventilation and solar heat gain.
Client AgencyAs used in connection with reimbursable National Weather Service (NWS) fire weather services, a public fire service or wildlands management agency…
ClimateThe prevailing or average weather conditions of a geographic region.
Climate Action PlanA description of the policies and measures that a local government will take to reduce greenhouse gas emissions and achieve its emissions reduction…
Climate ChangeA term used to describe short and long-term affects on the Earth's climate as a result of human activities such as fossil fuel combustion and vegetation…
Climate Diagnostics Bulletin(CDB) - The monthly CPC Bulletin reports on the previous months' status of the ocean-atmosphere climate system and provides various seasonal ENSO-related…
Climate Diagnostics Center(CDC) - The mission of NOAA's Climate Diagnostics Center is to identify the nature and causes for climate variations on time scales ranging from a month…
Climate FeedbackAn interaction mechanism between processes in the climate system is called a climate feedback, when the result of an initial process triggers changes in a…
Climate LagThe delay that occurs in climate change as a result of some factor that changes only very slowly.