Higher temperatures influence ozone formation in the lower atmosphere. Which statement is most accurate?

• A. Higher temperatures increase ozone formation; wind disperses pollutants; precipitation washes out soluble pollutants.
• B. Higher temperatures decrease ozone formation; winds always increase concentrations; precipitation increases concentrations.
• C. Temperature has no effect on ozone formation; only sunlight matters.
• D. Higher temperatures worsen precipitation and reduce pollutant washout.

Answer: (A)

Ozone formed near the ground comes from photochemical reactions among NOx and volatile organic compounds (VOCs) in sunlight. Warmer temperatures boost these reactions and also increase VOC emissions, especially from vegetation, so the chemistry that creates ozone proceeds more readily in hot conditions. Wind helps by diluting and moving pollutants, which can spread the potential for ozone formation or reduce local peaks. Rain and mist remove soluble pollutants from the air, lowering the amounts of precursors and oxidants available to form ozone. Taken together, higher temperatures tend to enhance ozone formation in the lower atmosphere, while wind dispersion and precipitation remove pollutants and can modulate that formation.