Is there any chance of a definition of low medium and high clouds?
In general (in middle latitudes):
Low clouds are those with cloud bases up to 7.000ft.
High clouds have bases from 18.000 ft.
Medium clouds range from 7.000 to 18.000ft.
Because the thickness of the troposphere (were the weather phenomena occur) ranges from 22.000 ft (poles) to 60.000ft (tropics), the definition of low, middle and high clouds vary from country to country.
Weather models usually use the above mentioned catigorization.