Your local weather station alerts you to the fact that 'acid rain' is currently falling in your area.

Your local weather station alerts you to the fact that ‘acid rain’ is currently falling in your area. You are worried about the well-being of your garden in your backyard, and decide to temporarily cover up as many plants as you can with plastic sheets. Then you explain to your neighbors what ‘acid rain’ is, and how it negatively affects plants.