Optical refraction and dispersion in the atmosphere are very old topics recognised by the professional observatories. Simple explanation here
http://www.astrosurf.com/prostjp/Dispersion_en.html and you will find useful articles in the NASA ADS such as this one:
http://articles.adsabs.harvard.edu/c...IF&classic=YES
... which in table II lists the atmospheric refraction calculated using a theoretical model, vs actual measurements made at a couple of observatories. The agreement is good - 2" - down to 86 degrees zenith distance. On page 193 the article concludes that optical dispersion (red-blue) is typically 1% or less of the refraction, and isn't strongly influenced by the observers altitude, temperature or humidity.
A couple of more recent (amateur) references:
http://www.damianpeach.com/images/ar...on%20Peach.pdf
http://www.farhorizons.nl/articles/A...ctor%201_3.htm
There is also a means to correct it - a variable thin prism is inserted in the optical path in front of the focus, such that the prism is always perpendicular to the horizon (regardless of where the telescope is pointing) and the prism can be adjusted to introduce a small amount of dispersion compensating for that of the atmosphere, based on the zenith distance of the telescope. For high-resolution colour imaging and accurate spectroscopy this compensation is essential on a large telescope. It is possible to include a compensator on a small telescope at f/10 or slower, if you really wanted to, complete with the controls to rotate it and adjust it as the telescope moves. Examples:
http://www.astrosystems.nl/projects_...ie_correct.htm or
http://www.cloudynights.com/ubbthrea...1/Main/4572731
These are also useful for the keen lunar & planetary observers.