The trough line of a circular depression is the line, through the centre, perpendicular to the line of advance of the centre. During the passage of a depression over any given place the pressure at first falls and later rises; the trough line passes over the place during the period of transition from the falling to the rising barometer. The word trough is also used in a more general sense for any 'valley' of low pressure, and is thus the opposite of a 'ridge' of high pressure.
(or "U-shaped valley"): The steep-walled (though rarely vertical), broad-floored shape considered diagnostic of former mountain glaciation. Often contrasted to the "V" shape typical of mass wasting slopes feeding river systems.
A trough (of low pressure) is a pressure feature of the synoptic chart; it is characterized by a system of isobars which are concave towards a depression and have maximum curvature along the axis of the trough, or trough line. The trough is said to be deep or shallow, according as the maximum curvature of the isobars along the trough line is more or small, respectively, the former corresponds to the V shape referred to in the obsolete term 'v-shaped' depression.
In geology, a trough generally refers to a linear structural depression that extends laterally over a distance, while being less steep than a trench. A trough can be a narrow basin or a geologic rift. There are various oceanic troughs, troughs found under oceans; examples include the rift along the mid-oceanic ridge and the Cayman Trough.
Often recognized as a "Trough of Low Pressure". A Trough is an area of generally low atmospheric pressure. Troughs occur at all levels of the atmosphere. Upper level troughs drive airmasses toward the southeast usually causing stormy weather. Surface troughs often precede cold fronts causing a lowering of pressure and a wind shift.
A trough of low pressure is indicated by isobars extending outwards from an area of low pressure. It has associated with a trough line which often indicated on a synoptic chart. The pressure at a point on a trough is lower than that at an adjacent point on either side of the line.
A colloquial and descriptive name of the parabolic cylinder (surface of constant parabolic cross-section) used for collecting solar radiation along the focal length. Trough systems follow the path of the sun by pivoting on one axis (typically East-West or North-South), using shiny parabolic troughs to heat the collector fluid that passes through a tube at the focus. Below is an illustration from the Solar Radiation Data Manual for Flat Plate and Concentrating Collectors.
a solar tracking mirror, either one or two axes, that generally reflects sunlight onto a linear receiver that is perpendicular to and is in alignment with the sun and the central axis of the linear parabolic mirror
a channel generally longer than its width, open at the top, or fitted with a cover, which contains the material being conveyed. The shaped of the cross section depends on the type of conveyor or feed involved.
A long, hollow vessel, generally for holding water or other liquid, especially one formed by excavating a log longitudinally on one side; a long tray; also, a wooden channel for conveying water, as to a mill wheel.