Bighorn sheep have double-layered skulls shored with struts of bone for protection during their fierce head-butting. They also have a broad, massive tendon linking the skull and spine to help the head pivot and recoil from blows.
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Rate of change of hour angle of mean Sun at place of observation. T = 15
Larger solar elliptic constituent. See R2. Speed = 2T - h + p1 = 29.958,933,3
Feathers extending from the rear of the bird.
Under and uppertail coverts.
System for assigning a number to each tail feather.
Treble hooked lures with attachments on the tail that spin when reeled in.
See electric tape gauge.
The slow graduation of a rod, line, or leader, one end being thicker than the other.
A National Forest's annual goals for accomplishment for natural resource programs. Targets represent the commitment the Forest Service has with Congress to accomplish the work Congress has funded, and are often used as a measure of the agency's performance.
Part of the leg between the knee and the foot.
Forces generated from within the earth that result in uplift, movement, or deformation of part of the earth’s crust.
The study of the major structural features of the Earth’s crust or the broad structure of a region.
The capability of transmitting or retrieving data over long distance communication links, such as satellite or telephone.
Posterior corner of eye.
Having three periods in a constituent day. The symbol of a terdiurnal constituent is the subscript 3.
Stripe at tip of tail.
A horizontal or nearly horizontal natural or artificial topographic feature interrupting a steeper slop, sometimes occurring in a series.
Literally ‘land-formed’ sediment that has found its way to the sea floor. The term is applied (a) to sediments formed and deposited on land (e.g., soils, sand dunes) and (b) to material derived from the land when mixed in with purely marine material (e.g., sand or clay in a shelly limestone).
Feathers adjoining the secondaries.
tertiary tide station
A tide station at which continuous observations have been made over a minimum period of 30 days but less than 1 year. The series is reduced by comparison with simultaneous observations from a secondary control tide station. This station provides for a 29-day harmonic analysis. See tide station, primary control tide station, secondary control tide station, and subordinate tide station (1).
The indicated breaking strength of fishing line.
The line down the center of the main channel of a stream.
Threshold velocity: The maximum orbital velocity at which the sediment on the bed begins to move as waves approach shallow water.
Cover used by animals against weather. For elk, thermal cover can be found in a stand of coniferous trees at least 40 feet tall with a crown closure of at least 70%.
A layer in which the temperature decreases significantly (relative to the layers above and below) with depth. The principal ones are designated diurnal, seasonal, and main thermocline.
thermosteric anomaly (
The specific volume anomaly (steric anomaly) that would be attained if the water were changed isothermally to a standard pressure of one atmosphere. The specific volume anomaly with pressure terms omitted. See isanostere.
A cutting made in an immature stand of trees to accelerate growth of the remaining trees or to improve the form of the remaining trees.
Those plant or animal species likely to become endangered throughout all or a specific portion of their range within the foreseeable future as designated by the U.S. Fish and Wildlife Service under the Endangered Species Act of 1973.
Front part of the neck. Synonym(s): foreneck, jugulum, throat patch. In picture it is referred to as foreneck.
The depth of a hook from the gap to the bend.
Front part of the neck. Synonym(s): foreneck, throat, jugulum. In picture it is referred to as foreneck.
Part of the leg above the knee.
tidal bench mark
See bench mark
tidal bench mark description
A published, concise description of the location, stamped number or designation, date established, and elevation (referred to a tidal datum) of a specific bench mark.
tidal bench mark state index map
A state map which indicates the locations for which tidal datums and tidal bench mark descriptions are available.
A tidal wave that propagates up a relatively shallow and sloping estuary or river in a solitary wave form. The leading edge presents an abrupt rise in level, frequently with continuous breaking and often immediately followed by several large undulations. An uncommon phenomenon, the tidal bore is usually associated with very large ranges in tide as well as wedge shaped and rapidly shoaling entrances. Also called eagre, eager (for Tsientan, China bore), mascaret (French), pororoca (Brazilian), and bore.
Principally, those features relating to the time, range, and type of tide.
Tidal relations that remain practically constant for any particular locality. Tidal constants are classified as harmonic and non harmonic. The harmonic constants consist of the amplitudes and epochs of the harmonic constituents, and the non harmonic constants include the ranges and intervals derived directly from the high and low water observations.
A horizontal movement of the water caused by gravitational interactions between the Sun, Moon, and Earth. The horizontal component of the particulate motion of a tidal wave. Part of the same general movement of the sea that is manifested in the vertical rise and fall called tide. The United States equivalent of the British tidal stream. See tidal wave, tide, and current.
tidal current chart diagrams
A series of 12 monthly diagrams to be used with the Tidal Current Charts. Each diagram contains lines that indicate the specific tidal current chart of each series to use, and the speed factor to apply to that chart.
tidal current charts
Charts on which tidal current data are depicted. Tidal Current Charts for a number of important waterways are published by the National Ocean Service. Each consists of a set of charts giving the speed and direction of the current for each hour or equal interval of the tidal cycle, thus presenting a comprehensive view of the tidal current movement.
tidal current constants
See current constants.
tidal current station
See current station.
tidal current tables
Tables which give daily predictions of the times and velocities of the tidal currents. These predictions are usually supplemented by current differences and constants through which predictions can be obtained for numerous other locations.
See LUNAR DAY.
Difference in time or height between a high or low water at a subordinate station and a reference station for which predictions are given in the Tide Tables. The difference, when applied according to sign to the prediction at the reference station, gives the corresponding time or height for the subordinate station.
See National Tidal Datum Epoch and epoch
(1) Marshy or muddy areas covered and uncovered by the rise and fall of the tide. A tidal march. (2) (SMP) Marshy or muddy areas of the seabed which are covered and uncovered by the rise and fall of tidal water.
The interval of time between two consecutive like phases of the tide or tidal current.
A pool of water remaining on a beach or reef after recession of the tide.
(1) The total amount of water that flows into a harbor or out again with movement of the tide, excluding any fresh water flow. (2) (SMP) The volume of water present between mean low and mean high tide.
See RANGE OF TIDE
The height of tide as referred to the datum of a chart.
An interval at high or low water when there is no observable change in the height of the tide. The water level is stationary at high and low water for only an instant, but the change in level near these times is so slow that it is not usually perceptible.
British equivalent of United States tidal current.
A shallow water wave caused by the gravitational interactions between the Sun, Moon, and Earth. Essentially, high water is the crest of a tidal wave and low water, the trough. Tidal current is the horizontal component of the particulate motion, while tide is manifested by the vertical component. The observed tide and tidal current can be considered the result of the combination of several tidal waves, each of which may vary from nearly pure progressive to nearly pure standing and with differing periods, heights, phase relationships, and direction.
The practice of dividing a hydrographic survey area into discrete zones or sections, each one possessing similar tidal characteristics. One set of tide reducers is assigned to each zone. Tide reducers are used to adjust the soundings in that zone to chart datum (MLLW). Tidal zoning is necessary in order to correct for differing water level heights occurring throughout the survey area at any given time. Each zone of the survey area is geographically delineated such that the differences in time and range do not exceed certain limits, generally 0.2 hours and 0.2 feet respectively; however, these limits are subject to change depending upon type of survey, location, and tidal characteristics. The tide reducers are derived from the water levels recorded at an appropriate tide station, usually nearby. Tide reducers are used to correct the soundings throughout the hydrographic survey area to a common, uniform, uninterrupted chart datum. See tide reducers.
tidally driven circulation
The movement of fresh water and seawater that are mixed by the sloshing back and forth of the estuary in response to ocean tides.
Tidal marsh: Same as tidal flats.
The periodic rise and fall of the water resulting from gravitational interactions between Sun, Moon, and Earth. The vertical component of the particulate motion of a tidal wave. Although the accompanying horizontal movement of the water is part of the same phenomenon, it is preferable to designate this motion as tidal current. See tidal wave.
tide (water level) gauge
An instrument for measuring the rise and fall of the tide (water level). See ADR gauge, automatic tide gauge, Next Generation Water Level Measurement System, gas purged pressure gauge, electric tape gauge, pressure gauge, and tide staff.
tide (water level) station
The geographic location at which tidal observations are conducted. Also, the facilities used to make tidal observations. These may include a tide house, tide gauge, tide staff, and tidal bench marks. See primary control tide station, secondary control tide station, tertiary tide station, and subordinate tide station
A graphic representation of the rise and fall of the tide in which time is usually represented by the abscissa and height by the ordinate. For a semidiurnal tide with little diurnal inequality, the graphic representation approximates a cosine curve. See marigram.
The height of the tide above a specified level.
tide predicting machine
A mechanical analog machine especially designed to handle the great quantity of constituent summations required in the harmonic method. William Ferrel's Maxima and Minima Tide Predictor (described in Manual of Tides, U.S. Coast and Geodetic Survey, Appendix 10, Report for 1883) was the first such machine used in the United States. Summing only 19 constituents, but giving direct readings of the predicted times and heights of the high and low waters, the Ferrel machine was used for the predictions of 1885 through 1914. A second machine, developed by Rollin A. Harris and E. G. Fischer and summing 37 constituents, was used for the predictions of 1912 through 1965 (described in Manual of Harmonic Analysis and Prediction of Tides by Paul Schuremen, U.S. Coast and Geodetic Survey Special Publication No. 98, 1958). Predictions are now prepared using an electronic digital computer.
Height corrections for reducing soundings to chart datum (MLLW). A tide reducer represents the height of the water level at a given place and time relative to chart datum. Tide reducers are obtained from one or more tide stations within or nearby the survey area. Often, due to differing tidal characteristics over the survey area, the tide reducers obtained directly from a tide station must be corrected to adjust for time and range of tide differences in the various zones of the hydrographic survey area. See tidal zoning.
A tide gauge consisting of a vertical graduated staff from which the height of the tide can be read directly. It is called a fixed staff when secured in place so that it cannot be easily removed. A portable staff is one that is designed for removal from the water when not in use. For such a staff a fixed support is provided. The support has a metal stop secured to it so that the staff will always have the same elevation when installed for use. See electric tape gauge.
Tables which give daily predictions of the times and heights of the tide. These predictions are usually supplemented by tidal differences and constants by means of which additional predictions can be obtained for numerous other places.
Tables which give daily predictions of the times and heights of high and low waters. These predictions are usually supplemented by tidal differences and constants through which predictions can be obtained for numerous other locations.
See tidal wave.
The periodic change in magnitude and direction of gravity as caused by attraction of the Sun, Moon, and other members of the Solar system.
See EBB TIDE
See FLOOD TIDE.
See MIXED TIDES.
See NEAP TIDES.
See SEMIDIURNAL, SEMIDIURNAL TIDE.
See SLACK WATER.
See SPRING TIDES.
See WIND TIDE.
That part of the gravitational attraction of the Moon and Sun which is effective in producing the tides on the Earth. The force varies approximately as the mass of the attracting body and inversely as the cube of its distance. The tide-producing force exerted by the Sun is a little less than one-half as great as that of the Moon. A mathematical development of the vertical and horizontal components of the tide-producing forces of the Moon and Sun will be found in Coast and Geodetic Survey Special Publication No. 98.
The zone between the mean high water and mean low water lines. It is identical with intertidal zone (technical definition) when the type of tide is semi diurnal or diurnal.
A subscription software program providing users (with an IBM PC, AT, or compatible computer), on demand, access to observed and predicted water levels (and anomalies) in graphic or tabular form. The service acquires real-time water level data at 6-minute intervals from selected stations equipped with telephone telemetry and, with the predicted tide at the location, provides a video or printed display. See REALDATA.
tides, types of
The characteristic form of the tide with special reference to the relation of the diurnal and semidiurnal waves. Tides are sometimes classified as diurnal, semidiurnal and mixed, but there are no sharply defined limits separating the groups. The tide is said to be diurnal when the diurnal wave predominated and only a single high and single low water occur each day during the greater part of the month. The tide is semidiurnal when the semidiurnal wave predominates and two high and two low waters occur each tidal day with a relatively small inequality in the high and low water heights. In the mixed type of tide the diurnal and semidiurnal waves are both important factors and the tide is characterized by large inequality in the high or low water heights or in both. There will usually be two high and two low waters each day, but occasionally the tide will become diurnal.
Water activated by the tide generating forces and/or water affected by the resulting tide, especially in coastal and estuarine areas. Also, a general term often applied to the land and water of estuarine areas formed by postglacial drowning of coastal plain rivers.
A channel through which a tidal current flows.
Lures with rapid side-to-side movement
The classification of forested lands into land management alternatives according to how the land relates to management of the timber resource there.
A meridian used as a reference for time.
Time is measured by the rotation of the Earth with respect to some point in the celestial sphere and may be designated as sidereal, solar, or lunar, according to whether the measurement is taken in reference to the vernal equinox, the Sun, or the Moon. Solar time may be apparent or mean, according to whether the reference is to the actual Sun or the mean Sun. Mean solar time may be local or standard, according to whether it is based upon the transit of the Sun over the local meridian or a selected meridian adopted as a standard over a considerable area. Greenwich time is standard time based upon the meridian of Greenwich. In civil time the day commences at midnight, while in astronomical time, as used prior to 1925, the beginning of the day was reckoned from noon of the civil day of the same date. The name universal time is now applied to Greenwich mean civil time.
The end section of a leader (the part that the fly is tied to).
The first guide on the tip of a fishing rod.
Digit attached to the feet.
(1) Lowest part of sea- and portside breakwater slope, generally forming the transition to the seabed. (2) The point of break in slope between a dune and a beach face.
(1) Coastal formation of beach material developed by refraction, diffraction and longshore drift to form a 'neck' connecting a coast to an offshore island or breakwater (see also salient). (2) (SMP) A causeway-like accretion spit that connects an offshore rock or island to the main shore, or to another island.
A long narrow strip of land, projecting into a body of water.
A map on which elevations are shown by means of contour lines.
The form of the features of the actual surface of the Earth in a particular region considered collectively.
The combination of the tidal and non tidal current. The United States equivalent of the British flow. See current.
The horizontal component of a tide producing force vector (directed parallel with level surfaces at that geographic location).
A logging method that uses tractors to carry or drag logs from the stump to a collection point.
An extra hook added to the back section of a lure used to assure more hook ups when a
trailing edge of wing
Rear edge of the wing in flight.
A wall or jetty to direct current flow
The invasion of a large area of land by the sea in a relatively short space of time (geologically speaking). Although the observable result of a marine transgression may suggest an almost ‘instantaneous’ process, it is probable that the time taken is in reality to be measured in millions of years. The plane of marine transgression is a plane of uncoformityf. The reverse of a transgression is a regression.
The passage of a celestial body over a specified meridian. The passage is designated as upper transit or lower transit according to whether it is over that part of the meridian Iying above or below the polar axis.
transitional water (zone)
In regard to progressive gravity waves, water whose depth is less than one-half, but more than 1/25, the wave length, also called a shallow water wave.
A bar which extends approximately right angles to shorelines.
The time necessary for waves to travel a given distance from the generating area.
The site- specific location of a resource improvement activity.
fish strikes the lure
An opening in the forest created by even-aged silvicultural practices.
A long narrow submarine depression with relatively steep sides.
The act of enticing a predator fish to initiate a strike on a lure or bait.
A specialty grip that allows an angler to make much longer and accurate cast with the use of a trigger grip
Fishing while dragging artificial lures, live or dead baits behind a boat while in motion to entice game fish to strike
A small electric fishing motor that is mounted on the bow of a boat used to travel very slow with minimal amount of noise.
A specialty rod used to drag small or large lures behind a boat while in motion. Most often with all roller guides.
Tidal currents occurring semimonthly when the effect of the Moon's maximum declination is greatest. At these times the tendency of the Moon to produce a diurnal inequality in the current is at a maximum.
Tropic high water inequality (HWQ) is the average difference between the two high waters of the day at the times of tropic tides. Tropic low water inequality (LWQ) is the average difference between the two low waters of the day at the times of tropic tides. These terms are applicable only when the type of tide is semi diurnal or mixed. See tropic tides.
Tropic higher high water interval (TcHHWI) is the lunitidal interval pertaining to the higher high waters at the time of the tropic tides. Tropic lower low water interval (TcLLWI) is the lunitidal interval pertaining to the lower low waters at the time of the tropic tides. Tropic intervals are marked a when reference is made to the upper transit of the Moon at its north declination or to the lower transit at the time of south declination, and are marked b when the reference is to the lower transit at the north declination or to the upper transit at the south declination. See tropic tides.
The great tropic range (Go), or tropic range, is the difference in height between tropic higher high water and tropic lower low water. The small tropic range (Sc) is the difference in height between tropic lower high water and tropic higher low water. The mean tropic range (Mc) is the mean between the great tropic and the small tropic range. Tropic ranges are most conveniently computed from the harmonic constants. See tropic tides.
The greater flood or greater ebb speed at the time of tropic currents.
Tides occurring semimonthly when the effect of the Moon's maximum declination is greatest. At these times there is a tendency for an increase in the diurnal range. The tidal datums pertaining to the tropic tides are designated as tropic higher high water (TcHHW), tropic lower high water (TcLHW), tropic higher low water (TcHLW), and tropic lower low water (TcLLW).
The average period of the revolution of the Moon around the Earth with respect to the vernal equinox. Its length is approximately 27.321,582 days.
The average period of the revolution of the Earth around the Sun with respect to the vernal equinox. Its length is approximately 365.242,2 days. The tropical year determines the cycle of changes in the seasons, and is the unit to which the calendar year is adjusted through the occasional introduction of the extra day on leap years.
The lowest point in a propagating or standing wave. See low water and tidal wave. A long and broad submarine depression with gently sloping sides.
See WAVE TROUGH
A landform cut off, especially by erosion, and forming a steep side or cliff.
TSI (Timber Stand Improvement)
Actions to improve growing conditions for trees in a stand, such as thinning, pruning, prescribed fire, or release cutting.
A shallow water progressive wave, potentially catastrophic, caused by an underwater earthquake or volcano.
A North Pacific Ocean current setting northeastward in the East China Sea (in summer) and Sea of Japan. A segment of the Kuroshio System.
(1) A condition of a liquid due to fine visible material in suspension, which may not be of sufficient size to be seen as individual particles by the naked eye but which prevents the passage of light through the liquid. (2) A measure of fine suspended matter in liquids.
A flowing mass of sediment-laden water that is heavier than clear water and therefore flows downslope along the bottom of the sea or a lake.
Turbulent flow: Any flow which is not LAMINAR, i.e., the stream lines of the fluid, instead of remaining parallel, become confused and intermingled.
The conversion of the dominant vegetation in an area from forested to non-forested or from one species to another.
type of tide
A classification based on characteristic forms of a tide curve. Qualitatively, when the two high waters and two low waters of each tidal day are approximately equal in height, the tide is said to be semidiurnal; when there is a relatively large diurnal inequality in the high or low waters or both, it is said to be mixed; and when there is only one high water and one low water in each tidal day, it is said to be diurnal. Quantitatively (after Dietrich), where the ratio of K1 + O1 to M2 + S2 is less than 0.25, the tide is classified as semidiurnal; where the ratio is from 0.25 to 1.5, the tide is mixed, mainly semidiurnal; where the ratio is from 1.5 to 3.0, the tide is mixed, mainly diurnal; and where greater than 3.0, diurnal.