With rise in temperature thermal conductivity of air:

Thermal CONDUCTIVITY of any material is dependent on TWO things:i. The motion of free electronsii. Lattice vibrationsThe thermal conductivity of gases increases with TEMPERATURE. Thermal conductivity of liquids decreases with increasing temperature as the LIQUID expands and the molecules move apart. In the case of solids, because of lattice DISTORTIONS, higher temperatures make it difficult for electrons to flow, hence the thermal conductivity of metals decreases. In non-metals, electronic conductivity is practically non-existent and due to increase in phonon conduction, the thermal conductivity increases.