In a very simple model of the lower atmosphere, air has a constant density of 1.25 kg/m3. How much would the air pressure change over a height difference of 260 m?
weight air= 1.25kg/m^3*area*290m*9.8N/m
= area*1.25*290*9.8 N/m^2=
pressure=weight/area= 3.55kPa
That is the difference in pressure for the two heights.