# Storm Glass **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [October 17, 2010, 11:06am UTC](https://boards.straightdope.com/t/storm-glass/557431 "2010-10-17T11:06:26Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Man\_From\_Maine](https://avatars.discourse-cdn.com/v4/letter/m/7feea3/32.png) [@Man\_From\_Maine](https://boards.straightdope.com/u/Man_From_Maine)\ **Post date:** [October 17, 2010, 11:06am UTC](https://boards.straightdope.com/t/storm-glass/557431/1 "2010-10-17T11:06:26Z")
Cecil, Wow! You went to great lengths on this one. One thing that came to mind when looking at your rainfall criteria. Did you know that depending on the humidity level of the air that rain drops pass through the rain drops may never make it to the ground? So my point is, maybe it is raining and you just don’t know it. Thanks Paul ---
**Author:** ![Fir\_na\_tine](https://avatars.discourse-cdn.com/v4/letter/f/a587f6/32.png) [@Fir\_na\_tine](https://boards.straightdope.com/u/Fir_na_tine)\ **Post date:** [October 17, 2010, 12:11pm UTC](https://boards.straightdope.com/t/storm-glass/557431/2 "2010-10-17T12:11:21Z")
[The item being discussed](http://www.straightdope.com/columns/read/2963/can-storm-glasses-predict-the-weather) ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [October 17, 2010, 1:18pm UTC](https://boards.straightdope.com/t/storm-glass/557431/3 "2010-10-17T13:18:04Z")
Rain that evaporates before it falls on your head is not rain by any definition that would be useful in the context of weather prediction. ---
**Author:** ![Canadjun](https://avatars.discourse-cdn.com/v4/letter/c/76d3ee/32.png) [@Canadjun](https://boards.straightdope.com/u/Canadjun)\ **Post date:** [October 17, 2010, 1:43pm UTC](https://boards.straightdope.com/t/storm-glass/557431/4 "2010-10-17T13:43:13Z")
> [@Man\_From\_Maine](#): > > Cecil, > Wow! You went to great lengths on this one. > One thing that came to mind when looking at your rainfall criteria. Did you know that depending on the humidity level of the air that rain drops pass through the rain drops may never make it to the ground? So my point is, maybe it is raining and you just don’t know it. > Thanks > Paul I think you are referring to [virga](http://en.wikipedia.org/wiki/Virga). ---
**Author:** ![Una\_Persson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/una_persson/32/346_2.png) [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)\ **Post date:** [October 17, 2010, 2:24pm UTC](https://boards.straightdope.com/t/storm-glass/557431/5 "2010-10-17T14:24:58Z")
We did not use it to track humidity, for the reason that a historical review of the use of the storm glass showed it was unanimously touted as primarily a tool to predict, well, storms, for among other things attempting to prevent shipping and naval ship losses. See for example the testimony of Vice-Admiral Sir Robert Calder, who specifically credits storm glasses with allowing them to predict when a fierce storm was going to end, allowing the rescue of the _Goliath_. Fitzroy specifically recommended that the storm glass be put onto every ship in the British Navy to try to predict damaging storms - a condition of typically very high humidity at pretty much most times in temperate or tropical waters. In addition to this issue, humidity varied at our house quite a bit over a single day - I checked two random clear days in a series of clear days as an example back in September, and found that the relative humidity varied from about 30% to 85% over a 24-hour period. Therefore, we felt that trying to predict changes in humidity would have resulted in a tremendous amount of noise which would not yield useful information. Although **Cecil** did mention it, I must stress that reading storm glass crystals is an **incredibly** subjective thing. I referred to them as a “weather Ouija board.” Even if storm glasses actually had something going for them, somehow, user error would have to be high. I’m glad we made them instead of buying one for $179 (although the cost to make the first 6 glasses was about $50 a glass). ---
**Author:** ![Deeg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/deeg/32/2955_2.png) [@Deeg](https://boards.straightdope.com/u/Deeg)\ **Post date:** [October 21, 2010, 7:55pm UTC](https://boards.straightdope.com/t/storm-glass/557431/6 "2010-10-21T19:55:01Z")
What I want to know is, in Slug’s accompanying picture, who’s Una and who’s Fierra? ---
**Author:** ![Una\_Persson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/una_persson/32/346_2.png) [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)\ **Post date:** [October 21, 2010, 9:45pm UTC](https://boards.straightdope.com/t/storm-glass/557431/7 "2010-10-21T21:45:31Z")
> [@Deeg](#): > > What I want to know is, in Slug’s accompanying picture, who’s Una and who’s Fierra? Since I was the one who did most of the checking, I’m probably the one out in the rain. (and it’s neat to have a Slug illustration of oneself!)