Can bad weather conjure good moods? Between the 1950s and 1980s, scientists dedicated significant resources to studying whether the cheer that many of us feel during storms is the result of a more precise mechanism than mere “cozy vibes.” The theory advanced by biometeorologists (those who study the effects of weather on organisms and ecosystems) relates to the perceived effect of negative ions in the atmosphere. Negative ions are invisible molecules that have gained an extra electron. They occur naturally but are created in particular abundance by some meteorological events including downpours and lightning. Their existence is not in doubt.

What is less clear is their precise effect. In one study, researchers exposed people with seasonal affective disorder to high concentrations o...