Nation/World / News Q & A

Q: I recently read an article stating that in Phoenix and Tucson, Ariz., something called swamp coolers are used in lieu of air conditioning. What are swamp coolers and how do they work to cool the homes?

SANDRA GRELLA, Canton

A: Swamp or evaporative coolers use fans to pull dry outside air over a water-saturated pad where the air is cooled by evaporation and circulated by a blower wheel within the unit. Swamp coolers are better suited for climates where the air is hot and dry because it adds humidity to the air. According to the U.S. Department of Energy Web site at digbig.com/4tady, our edit of a longer Web address, windows or ceiling vents need to be open when a swamp cooler is working to allow warm indoor air to escape as it is replaced by cooled air.

Q: What does the "D" stand for in D-Day?

NOBLE HAMILTON JR., Greenbrae, Calif.

A: D stands for day or date. When planning for a military operation begins, the date and time often are represented as D-Day and H-Hour, because of secrecy concerns or because the date and time aren't set, or both. According to the U.S. Army Center of Military History's frequently asked questions Web page, the first use of these two abbreviations was in 1918 during World War I. But the term is forever linked to June 6, 1944, when the Allied invasion of German-occupied France began during World War II.

Staff researchers Joni Zeccola and Richard Hallman contributed to this column.