  The potential of photometric methods for the identification of l, the degree
of spherical surface harmonic of a pulsating star, is investigated with special
emphasis on Stromgren photometry applied to delta Scuti and gamma Dor
variables. Limitations of actual model atmospheres when fine precision is
required for the calculations of partial derivatives and integrals, which
depend on limb darkening coefficients, are discussed. Two methods are discussed
to calculate the phase lags, the angle between maximum temperature and minimum
radius, and R, a parameter which describes departure from adiabaticity of the
atmospheres of these pulsating stars. These quantities appear to be very
dependent on the convection as parametrized by the mixing length theory. When
one of the methods is applied to the gamma Dor stars gives phase lags close to
0 degrees, which are 90-180 degrees out of phase from typical delta Scuti
stars. Examples are given for some High Amplitude Delta Scuti Stars (HADS)
where the method can be easily applied and gives results consistent to
interpret them as radial (l=0) pulsating stars. Other low amplitude delta Scuti
stars could be oscillating in a non-radial (l=1, 2) mode. Multi-band photometry
is concluded to be a very powerful tool for mode identification of delta Scuti
and gamma Dor stars, specially with the more accurate photometry that will be
achieved in the near future with the asteroseismological space missions now in
progress.
