Miata Mailing List: October 1994, Message #93
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   From: Piet.Ruyssinck@rug.ac.be (Piet Ruyssinck)
Subject: monoxide levels in the winter
   Date: Thu, 6 Oct 1994 04:18:09 -0400


> > Carbon monoxide levels are greater in the winter.  I can't explain why,
> > but they are.  I think it has to do with colder air.  CO levels are also
> > greatest in the early morning, rather than in the afternoon like most
> > other pollutants.  As you can see, I'm no meteorlogist either, but I
> > do get involved in air pollution research some (mostly ozone, though,
> > since I'm in Southern California).

I think it has to do with the following (I'm not a meteorologist either) :

Normally (summer), the temperature on the surface of the earth is higher
than that of the layers of air above it.  So, the exhausts go
upwards.  See great ascii drawing (temp in Centigrades, height in km)

temp |
     |
 30  |\
     | `\
 20  |   `\
     |     `\
 10  |       `\
     |         `\
  0  |           `\
     |             `\
-10  |               `\
     |                 `\
-20  |                   `\
     |                     `\
-30  |                       `\
     |                         `\
-40  |                           `\
     |                             `\
-50  |__________________________________________ height
     0   1   2   3   4   5   6   7   8   9   10 

In the winter, there's sometimes this thing called 'inversion'
(literal translation of the Flemish word for it) as the following 
graph shows.  This prevents the exhausts from escaping to the higher
air layers

temp |
     |
 30  |
     |
 20  |
     |
 10  |
     |    __----.
  0  | _--       `\
     |-            `\
-10  |               `\
     |                 `\
-20  |                   `\
     |                     `\
-30  |                       `\
     |                         `\
-40  |                           `\
     |                             `\
-50  |__________________________________________ height
     0   1   2   3   4   5   6   7   8   9   10
 

Hope this explains it a bit,
Piet

________________________________________________________
Piet RUYSSINCK                  Piet.Ruyssinck@rug.ac.be
Department of Data Analysis               +32 9 264 4733
University of Ghent (RUG)                               
Krijgslaan 281, building S9 (ARC), B-9000 Ghent, Belgium