Ava Marie, meteorologist at WBAL, an NBC affiliate in Baltimore, shared an interesting radar view Monday morning. What looked like a very localized thunderstorm was actually the Chesapeake Bay Bridge reflecting the radar beam.

This was created by atmospheric ducting, the refraction or guiding of electromagnetic radiation to follow the curvature of the Earth. The result whether it is radio waves or light being bent is “seeing” things that are below the horizon.

Dutch astronomer Willebrord Snellius described the law of refraction (also known as Snell’s law) in 1621 while working on an experiment to determine the Earth’s radius. He described, in mathematic form, how increasing altitude along with pressure and temperature decrease causes a light waves to change direction.

This is demonstrated with each sunrise and sunset as well. The lower, warmer layers near the horizon do an excellent job of refracting sunlight. When you first spot the upper limb of the Sun at sunrise, it is actually still about half a degree below the horizon. It's not a huge difference, but this morning that allowed us to see the sunrise 17 seconds early.

During major meteor showers (such as the upcoming peak of the Perseids), radio waves can be reflected off the trail of ionized air left by meteors entering the upper atmosphere. This enables radio stations below the horizon to be received if just for a second or two.

The Department of Agriculture’s SNOwpack TELemetry (SNOTEL) system has taken advantage of even small meteor bursts to transmit information about watersheds up to 1,200 miles away since the 1960s. While this seems like something that would work only sporadically, the USDA reports a 95-99 percent response rate from 730 SNOTEL sites across 11 western states. Conversion of key sites to cellular technology has enabled hourly readings to be transmitted.