•Barotropic
 Atmosphere
 •èno temperature
 gradient on pressure surfaces 
 èisobaric surfaces are also the isothermal surfaces 
 èdensity is only function of pressure ρ=ρ(p)
 è no
 thermal wind
 è no
 vertical shear for geostrophic winds
 è geostrophic
 winds are independent of height
 è you can
 use a one-layer model to represent the barotropic atmosphere