Complex sentence: An-4 is the design bureau designation for the An-2ZA, a variant of the An-2 intended specially forthe role of high-altitude meteorological research with a glazed position immediately in front of the tail fin for an observer.
Split into simpler sentences: An-4 is the design bureau designation for the An-2ZA, a variant of the Antonov An-2 intended specially for high-altitude meteorological research. It has a glazed position immediately in front of the tail fin for an observer.