| Section T | T index | 311-319 of 589 terms |
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time-of-arrival technique—The time-of-arrival technique refers to locating the source of an emitted signal from a precise recording of the time that a signal is observed. For example, the time interval between an observed lightning flash and the arrival of the thunder can be used to estimate the distance to the lightning flash. On the average, a time arrival difference of five seconds indicates that a lightning flash occurred one mile away from the observer, since the speed of sound in air is approximately 1000 ft s−1.
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time of concentration—An expression of the length of time it takes for water to travel from some designated geographical location of the watershed to another, or from some identifiable time on the histogram of the runoff-causing event to the time of peak or centroid of the storm hydrograph.
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time section—(Also called time cross section.) A diagram in which one coordinate is time and the other is distance (usually height, in which case it is a vertical time section). Compare cross section, profile, time–height section.
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time series—The values of a variable generated successively in time. A continuous barograph trace is an example of a continuous time series, while a sequence of hourly pressures is an example of a discrete time series. Graphically, a time series is usually plotted with time as the abscissa and the values of the function as the ordinate. Time series may be either stationary or nonstationary. For stationary time series the actual dynamics that motivate the series are constant from one period to the next. For nonstationary time series the dynamics are continually changing and such series are less susceptible to statistical analysis.
Wadsworth, G. P., 1951: Compendium of Meteorology, 849–855.
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time—Duration as measured by some clock. Atomic clocks give the most accurate measure of time. Less regular timekeepers are those based on the rotation of the earth and other bodies of the solar system.
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tipping-bucket rain gauge—A recording rain gauge in which the water collected continuously drains through a funnel into one of a pair of chambers or buckets that are balanced bistably on a horizontal axis. When a predetermined amount of water has been collected, commonly 0.25 mm (0.01 in.) of rain, the bucket tips, spilling the water and placing the other bucket under the funnel. An electronic switch is excited each time the bucket tips so that both rain rate and accumulation can be determined from the record of tips.
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tivano—A night breeze blowing down the valley at Lake Como in Italy.
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