Low-pressure area area of wind divergence aloft occurs ahead of embedded shortwave troughs, which are of smaller wavelength. Diverging winds aloft ahead of these troughs cause atmospheric lift within the troposphere below, which lowers surface pressures as upward motion partially counteracts the force of gravity. Thermal lows form due to localized heating caused by greater sunshine over deserts and other land masses. Since localized areas of warm air are less dense than their surroundings, this warmer air rises, which lowers atmospheric pressure near that portion of the Earth's surface. Large-scale thermal lows over continents help drive monsoon circulations. Low-pressure areas can also
High pressure metamorphic terranes along the Bangong-Nujiang Suture Zone are generally associated with subduction zones. Protoliths of serpentinites are olivine- and pyroxene-dominated. The formation of serpentinites is caused by the release of fluids from subducting hydrated oceanic slabs as they become heated with depth to a maximum temperature of 650-700 °C. Eclogites are high-pressure (HP) to ultrahigh-pressure (UHP) metamorphic rocks that are indicative of subduction zone metamorphism. The eclogites in central Tibet are of Early Mesozoic origin, and they appear to be the result of diachronous collision between the eastern Qiangtang terrane and the western Qiangtang-Lhasa plate, along the linked eastern Bangong-Nujiang-central Qiangtang zone. Located along the western sector