
Dear Tom,
Since hurricanes develop over saltwater oceans, does any of the rain come
down as salt water?
John
Dear John,
A raindrop is pure water (with the exception of the condensation nucleus
around which it initially formed and any pollutants such as smoke or
bacteria it might have picked up from the atmosphere). Rainwater is pure
because materials like salt dissolved in ocean water remain behind when
water evaporates from the ocean surface, and that's fortunate because sea
water contains a great deal of salt.
Herbert Swenson of the U.S. Geological Survey tells us ocean water contains
about 35 pounds of salt per 1,000 pounds of water. One inch of rain across
Chicago's 228.5 square miles of area yields 33.1 billion pounds of water. If
rainwater contained salt at the concentration of ocean water, 1.2 billion
pounds of salt would accompany every one-inch rain across the city.
WGN-TV Chief Meteorologist Tom Skilling and the WGN Weather Center staff provide daily coverage of weather in the Chicago area.
