What is the main idea of the passage?

Petrichor forms when raindrops release soil compounds and plant oils into the air. (The passage traces the scent from materials on the ground through bubbles and airborne particles.)

Why can light rain produce a strong effect?

Its drops may trap bubbles without quickly washing the scented material away. (The final paragraph contrasts bubble-forming light rain with downpours that may wash material away.)

What does “airborne” mean?

carried through the air (The particles travel into the air and toward a nose, so airborne means carried in air.)

What compound is produced by certain soil bacteria?

geosmin (The opening paragraph directly identifies geosmin as a compound made by some soil bacteria.)

The Smell After Rain: Level 2 Reading Comprehension Questions

After rain reaches dry ground, the air may carry an earthy smell called petrichor. The scent does not come from water alone. Plants leave oils on soil and stone during dry weather. Certain soil bacteria also produce a compound called geosmin.

When a raindrop hits a porous surface, tiny air bubbles can form beneath it. The bubbles rise through the drop and burst. They release a fine mist of particles into the air. Those particles can carry geosmin and plant oils toward a person's nose.

Light rain can produce the effect especially well because drops strike gently enough to trap bubbles. A hard downpour may wash material away before much becomes airborne. Wind, soil type, and the length of the dry spell also change what people smell. Petrichor is therefore not the odor of rain itself. It is a brief airborne mixture released when rain meets a particular landscape.

Comprehension questions