With a great heaviness in my heart, I must report that some writers often mix up lightning and lightening.

Lightning is the flash of light that accompanies thunder: The lightning lit up the room as if it were daytime.

Lightening, however, is a reduction of weight, either literally or figuratively: The hikers sat against the boulders, lightening the load on their tired feet.

A quick memory tip: lightening has an “e” in it and so is the “heavier” word.