How many letters does the top answer for “pertaining to the measurement of wind speed and direction” have?

The most common answer is anemometric (11 letters).

Crossword clue: pertaining to the measurement of wind speed and direction

1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

anemometric 11 letters wn-def

pertaining to the measurement of wind speed and direction

measuring wind speed and direction 50% similar → anemometry