[Author Index] [Date Index] [Thread Index]
[Date Prev][Date Next][Thread Prev][Thread Next]

[ST] The Final Answer.....



OK - this was really bothering me, so I emailed the National Weather
Service (and no less, the station in Corpus Christi, TX).  

Matt Heyer


- -----Original Message-----
From: SR-CRP Webmaster [mailto:SR-CRP.Webmaster@xxxxxxxx] 
Sent: Wednesday, March 16, 2005 11:18 AM
To: Heyer, Matthew A.
Subject: Re: Relative Humidity Question

Heyer, Matthew A. wrote:

> Hi - I hope this is the correct forum to find this out, but I'm not 
> sure. If not, if you could please direct me to where I can get this 
> answered, I would appreciate it. My question is as follows:
>
> In speaking with someone recently, they were talking about the weather

> in the Corpus Christi area. More specifically they were speaking of 
> the hot summers, which they say included 132% Relative Humidity days.
> From my knowledge of relative humidity, I thought that relative 
> humidity could only go up to 100% (the air being saturated as it is 
> holding its maximum absolute humidity). And subsequently, that once 
> the relative humidity reaches 100%, water vapor condenses out of the
air.
>
> So, is relative humidity over 100% possible? (if so, is that fog?) And

> do you actually get weather with 132% relative humidity? Regularly or 
> ever?
>
No. Relative humidity is the ratio of the amount of water vapor in the
air to the amount of water air could hold at that temperature. At 100%
relative humidity, the air is holding as much water vapor as it possibly
can at that temperature.

In certain, relatively rare situations, thunderstorms can briefly create
what's called "supersaturation", where relative humidity values exceed
100%. This occurs when cloud droplets are condensing so fast that they
run out of condensation nuclei to condense onto. This behavior only
occurs in small parts of certain thunderstorms, and even then is very
brief, since our atmosphere has condensation nuclei in abundance.

Fog occurs when condensation occurs very close to the ground, often
underneath a temperature inversion that prevents the air from mixing
with air above it. Just think of fog as being clouds very close to the
ground. Relative humidities are often near 100% when fog occurs, but not
over 100%.

Thanks for your interest in our web site!

Best regards,

The NWS Corpus Christi Web Team




     *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *
      The ST/RS Mailing list is sponsored by Jack Lilley Ltd.
          http://www.TriumphNet.com/st/lilley for more info
   http://www.TriumphNet.com/st for ST, RS and Mailing List info

=-=-=-= Next Message =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=