Atmosphere Ocean Science Colloquium

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Implications of Weak Temperature Gradients for the Tropical Atmosphere

Speaker: Yi Zhang, NYU

Location: Warren Weaver Hall 1302

Date: Wednesday, November 19, 2025, 3:30 p.m.

Synopsis:

The tropical atmosphere feels a weak Coriolis effect, therefore horizontal pressure gradients in the free troposphere are weak on planetary scales - this is the well-known weak temperature gradient (WTG) assumption. WTG places strong constraints on the tropical atmospheric dynamics. We show how WTG homogenizes the boundary layer moist static energy whenever and wherever there is deep convection. An unexpected implication is a scaling for changes in extreme wet-bulb temperatures, which is a metric for humid heat stress. Finally, we show that weak temperature gradients will likely become weaker with warming due to increased atmospheric stratification.