Met Mailbag is your chance to have a Weather Plus Meteorologist answer your weather question. Each Thursday, our NBC Weather Pulse Blog will publish the answers to questions you send us. This week's questions were answered by NBC Weather Plus Meteorologist Jeff Ranieri

Question: What is ice fog?
Submitted by Al Hurvitz, San Francisco, Calif.

Answer: Al, Since you're from California I’m sure you are a fog expert on many levels but the reason why you may not know about ice fog has a lot to do with the temperatures.

Ice fog is generally formed in higher elevations or a region that is super cold. Just like with ground fog… temperature, a moisture source, and calm winds are all key factors. Ice fog forms when the temperature is minus 30 F and below. So, with super cold temperatures the moisture freezes into ice particles at the lower levels.

So if you want to actually see the ice fog on something other than your computer, a trip to the poles may be your only way to catch a glimpse!