1. The problem statement, all variables and given/known data Hello, I need a) to Sketch φ which is the geopotential field, dependent on four variables (x,y,z,t) b) to Sketch the geopotential at 2.5 and 7.5 km altitude 2. Relevant equations φ(x,y,z,t) = φ0(z) + c * f0 ( -y ( cos(π * (H-z)/H ) + 1 ) + 1/k * sink(x-ct)) 3. The attempt at a solution Well ... i know that c is a speed, k is the zonal wave number, but there are no numbers given - and I really have no clue how to start. Thanks for help!