Science / Tides and Currents / Trough: The lowest point in a propagating wave. See low water and tidal wave.
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Pre-Frontal Trough

Science / Weather / Pre-Frontal Trough: An elongated area of relatively low pressure preceding a cold front that is usually associated with a shift in wind direction. MORE

Long Wave Trough

Science / Weather / Long Wave Trough: A wave in the prevailing westerly flow aloft which is characterized by a large length and amplitude. A long wave moves slowly and is persistent. Its position and intensity govern weather patterns over MORE

Equatorial Trough

Science / Weather / Equatorial Trough: The quasi-continuous area of low pressure between the subtropical high pressure areas in both the Northern and Southern Hemisphere. MORE