# Freezing Fog Warning? **URL:** \ **Category:** Factual Questions\ **Created:** [December 23, 2010, 5:22am UTC](https://boards.straightdope.com/t/freezing-fog-warning/565158 "2010-12-23T05:22:35Z")\ **Posts on this page:** 5\ **Page:** 2
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [December 26, 2010, 4:12am UTC](https://boards.straightdope.com/t/freezing-fog-warning/565158/21 "2010-12-26T04:12:39Z")
> [@Critical\_Mass](#): > > …it is gradually accumulating ice on the control surfaces, degrading handling characteristics, increasing overall weight, the pilots are suffering from reduced visibility and all this at a critical phase of flight while the airspeed is slowing and precision handling is imperative. Not nice stuff to airplanes. The biggest issue is that the ice tends to form on the upper surface of the wing in the areas of greatest curvature. \* (near the front) This causes airflow disruption which increases drag and reduces lift. At best it decreases performance and increases stall speed. At worst the airplane literally becomes unable to fly. Propellers would have the same issue, but are spinning fast enough to sling the ice off. \*If an airplane has de-icing, this is the area where you will always find de-icing systems. Some aircraft will have additional de-icing systems in other areas. ---
**Author:** ![elfkin477](https://avatars.discourse-cdn.com/v4/letter/e/a9a28c/32.png) [@elfkin477](https://boards.straightdope.com/u/elfkin477)\ **Post date:** [December 26, 2010, 8:39am UTC](https://boards.straightdope.com/t/freezing-fog-warning/565158/22 "2010-12-26T08:39:02Z")
> [@Twoflower](#): > > Freezing fog can happen in California, too. Happens some times in the Sierra foothills, when the cold mountain air overlaps with the valley fog. Roads get _very_ slick when the fog droplets freeze into a smooth layer on the asphalt. > [@fachverwirrt](#): > > It’s called [rime](http://en.wikipedia.org/wiki/Rime_ice). > > It’s particularly prevalent on Mt. Washington, NH, where you get stuff like [this](http://scenicnh.photoshelter.com/image/I0000teA5Hg5ZfZg). So, when it happens in CA, is it in areas where people would really be driving? As **fachverwirrt** notes, it happens on Mt. Washington, but a. I’ve never heard of it happening _anywhere_ but there in this state b. in the winter the people at the weather observatory are pretty much the only ones at the top of the mountain during the winter, so motorists aren’t likely to encounter it. ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [December 26, 2010, 11:26pm UTC](https://boards.straightdope.com/t/freezing-fog-warning/565158/23 "2010-12-26T23:26:35Z")
> [@dolphinboy](#): > > Thanks everyone! Now I know… \…and knowing is yadada-yadada.\:D ---
**Author:** ![Oslo\_Ostragoth](https://avatars.discourse-cdn.com/v4/letter/o/a9a28c/32.png) [@Oslo\_Ostragoth](https://boards.straightdope.com/u/Oslo_Ostragoth)\ **Post date:** [December 27, 2010, 5:53am UTC](https://boards.straightdope.com/t/freezing-fog-warning/565158/24 "2010-12-27T05:53:02Z")
Black ice is a possibility. The most evil thing imaginable - the road is covered with Teflon-quality ice, but you can’t see it. ---
**Author:** ![Cat\_Whisperer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cat_whisperer/32/4839_2.png) [@Cat\_Whisperer](https://boards.straightdope.com/u/Cat_Whisperer)\ **Post date:** [December 28, 2010, 12:00am UTC](https://boards.straightdope.com/t/freezing-fog-warning/565158/25 "2010-12-28T00:00:43Z")
> [@Oslo\_Ostragoth](#): > > Black ice is a possibility. The most evil thing imaginable - the road is covered with Teflon-quality ice, but you can’t see it. I posted a couple of weeks ago that black ice is proof that God hates us and wants us all to die. 🙂 [Previous page](https://boards.straightdope.com/t/freezing-fog-warning/565158.md?page=1)