ALL meanings of d region
d re·gion
D d - noun d region the lowest region of the ionosphere, extending from a height of about 60 kilometres to about 90 kilometres: contains a low concentration of free electrons and reflects low-frequency radio waves 3
- noun d region the lowest atmospheric zone within the ionosphere, at an altitude of c. 55 to 90 km (c. 34 to 56 mi), containing the D layer 3
- noun d region the lowest region of the ionosphere, in which the D layer develops. 1