Q Does rainfall bring any nitrogen (fertilizer) to plants and lawns?

A Yes, lightning that accompanies thunderstorms can act to add nitrogen to the soil. Gaseous nitrogen (which makes up about 78 percent of the atmosphere) is unusable by higher plants because of its chemical composition. Nitrogen is transformed to a plant-usable form (nitrogen fixation) by the electrical discharges that can occur within thunderstorms.

The usable nitrogen is added to the soil as a component of precipitation. While this process is beneficial to plants, the vast majority of nitrogen fixation is accomplished by microorganisms in the soil.

Greg Spoden, assistant state climatologist

Flu naming

Q The latest swine flu virus is supposed to be something new and unique, by all accounts. Yet it's referred to as strain H1N1, which is the designation of a whole bunch of previous flu viruses dating back decades. Shouldn't it be called something else? 

A Probably. The label H1N1 can be confusing because it is a designation used in previous influenza strains, human, bird, as well as swine, according to Lynn Bahta with the Minnesota Department of Health. The difference is in the genetic makeup of the proteins of the virus. This name identifies that the proteins that make up the H and the N come from three biologic sources -- humans, birds, and swine. This also makes this H1N1 virus unique, a virus that no one has immunity to.

The naming of the virus is still evolving. Most say H1N1, some say swine, others wanted to call it Mexican flu, but that's no solution. Experts aren't sure that it actually started in Mexico. The previous pandemic of a similar swine flu was called the Spanish flu for a long time. But Spaniards called it the French flu. For now, the name for this one appears to be 2009 H1N1 flu, or simply H1N1.

Send your questions to Fixit in care of the Star Tribune, 425 Portland Av., Minneapolis, MN 55488, or call 612-673-7032, or e-mail fixit@startribune.com. Past columns are available at www.startribune.com/fixit. Sorry, Fixit cannot supply individual replies.