Your word of the day is "Pantograph," as in "What is a pantograph?"

A few of you noticed some problems with RTD's light rail Monday morning. One commuter on the lines that run along I-25 reported that the lights flickered and turned off. Another tweeted at RTD at 4:29 a.m.:

RTD's response:

Which brings us back to that pesky "pantograph" word (sorry RTD, you spelled it wrong). It's the arm that's on top of light rail trains that give the light rail power as long as the arm is in contact with the overhead wires.

It's like a Jacobs Ladder, that arc you played with in science class or see in any monster creation movie.

We went to the Denver Museum of Nature and Science to understand how freezing rain can delay a light rail commute.

"If (the wire) gets too much ice around it, the pantograph will come across and just hit ice, and ice in this case acts like an isolator. It doesn't allow electricity to flow through it," said Denver Museum of Nature and Science Educator Brian Hostetler.

Snow doesn't cause the same effect.

"There's enough air in between bits of snow that electricity still finds its way through, but ice is much denser," said Hostetler.

An RTD spokesman said that light rail has never shut down because of ice. One reason may be because Denver doesn't get thick ice storms like elsewhere in the United States. Another reason is because the trains run constant enough that ice doesn't have time to build up.

And a third reason is provided by RTD on Twitter:

Marshall Zelinger is an investigative reporter for Next with Kyle Clark. Have a tip? Story idea? Email or call 303.349.0784.