|WHAT IS A THERMAL TROUGH (RIDGE)?
METEOROLOGIST JEFF HABY
A thermal trough is a region of synoptic scale cooler temperatures while a thermal ridge is a region of synoptic
scale warmer temperatures. The word thermal is a descriptor of temperature, trough a descriptor of "lower values",
and ridge a descriptor of "higher values". Thermal troughs and ridges are closely related to the
trough and ridge
height contour patterns. Thermal troughs tend to be located underneath height contour troughs (behind cold front)
and thermal ridges tend to be located underneath height contour ridges. Thermal ridges are common in the warm sector
of a mid-latitude cyclone. This region often experiences
WAA. A synoptic region of strong CAA will
create a thermal trough
while WAA a thermal ridge. The
jet stream and mid-latitude cyclones propagate the thermal field.
forecasting: (1) regions under thermal troughs tend to be cooler than normal, ridges warmer than normal, (2)
thermal ridges often are indicators of higher
instability regions especially if WAA and
moisture advection are associated with the thermal ridge.