What is the effect of increase in temperature on viscosity of gases

Viscosity of gases increases with temperature. As temperature rises, gas molecules move faster and exchange momentum more often, which increases internal friction (viscosity). 

This trend is captured by Sutherland’s law, a widely used relation in aerodynamics and hightemperature gas flow, which shows μ ∝ T^{3/2}/(T + S) (μ = viscosity, T = absolute temperature, S = Sutherland constant). 

In contrast, liquids generally show the opposite behavior (viscosity decreases with temperature), so state clearly that the question is about gases. In numerical problems, engineers often apply Sutherland’s formula between reference and operating temperatures to estimate μ(T). Key takeaway: Higher T → higher μ for gases due to increased molecular collisions and momentum transfer.