Interference of surface waves

Two point sources emit surface waves that interfere with each other. The amplitudes of the waves emitted by the two sources are given by,

Where r₁ is the position of source 1 and r₂ is the position of source 2. The wavenumber k is related to the wavelenth λ, k = 2π/λ, and the angular frequency ω is related to the period T, ω = 2π/T.

Red is positive and blue is negative. Black regions have no wave amplitude.