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 nervous syndrome the West until 1967. The term "high-pressure nervous syndrome" was first used by Brauer in 1968 to describe the combined symptoms of tremor, electroencephalography (EEG) changes, and somnolence that appeared during a chamber dive in Marseille. Symptoms of HPNS include tremors, myoclonic jerking, somnolence, EEG changes, visual disturbance, nausea, dizziness, and decreased mental performance. HPNS has two components, one resulting from the speed of compression and the other from the absolute pressure. The compression effects may occur when descending below at rates greater than a few metres per minute, but reduce within a few hours once the pressure has stabilised.