In the article theoretical bases of existence of troposphere radiowaveguides are considered above a sea. On the basis of analysis in the theory of distribution of radio waves of literature it is rotined known, that in practice of radio-location at the study of processes, which take a place in troposphere radiowaveguides above a sea, most informing there is the modified index of refraction. His dependence is illustrated on the hydrometeorological parameters of troposphere and on the basis of analysis of his world-modeling classification of troposphere radiowaveguides formation of which possibly above a sea is conducted. Parameters over of radiowaveguides which most often arise up above a sea are brought.
in-superficial, brought radiowaveguide, coefficient and index of refraction