As the cause of the diurnal change in barometric pressure, the author proposes two elementary changes: the thermal effect Δp and the dynamical effect Δπ, i.e. dp(τ) = Δp(τ) + Δπ(τ). Here, dp(τ) is the diurnal variation in barometric pressure and

Δp=c·∂²θ(τ)/∂τ²=2cβθ₀2{β(τ-13)²-1}^e-β(τ-13)2
Δπ=c·ΔP_h=-c·(ρu{u₀e^-r(τ-3)2+u-u)_h}

where c, β, γ and c, u are all constants, θ₀ and u₀ the diurnal ranges of air temperature and upper wind speed respectively, ρ and u the mean density and mean wind speed in upper air layer respectively, e the Napier's constant and τ the local time.