Question

Intensity of drizzle is:

• A. Greater than 3 mm/h
• B. Between 1 mm/h to 2 mm/h
• C. Less than 1 mm/h
• D. Between 2 mm/h to 3 mm/h

Hint:

Drizzle has droplets \(\lt 0.5 \text{ mm}\) and intensity \(\lt 1 \text{ mm/h}\).
These parameters distinguish it from light rain (which has larger drops and higher intensity).

Answer 1

The Correct Option is C

Step 1: Recall how precipitation types are distinguished.
Rain and drizzle are both liquid precipitation but are classified separately based on droplet size, drizzle consists of very fine, closely spaced water droplets with a diameter smaller than about 0.5 mm falling from low stratus-type clouds, whereas rain consists of larger drops falling from deeper convective or nimbostratus clouds.
Step 2: Recall how rainfall intensity is graded for comparison.
Ordinary rain intensity is graded roughly as light up to about 2.5 mm/h, moderate between 2.5 and 7.5 mm/h, and heavy above 7.5 mm/h.
Step 3: Place drizzle on this intensity scale.
Because drizzle droplets are so small and settle so slowly, the liquid water flux they deliver to the ground is always very low, conventionally taken as an intensity of less than 1 mm/h, any measured rate higher than this is reclassified as light rain rather than drizzle.
\[ \boxed{Less than 1 mm/h} \]