Chicago Fog

Chicago Fog
Chicago fog

Have you ever wondered what it would be like to live among the clouds?  Fog could be called clouds at ground level.  Like clouds, fog is composed of condensed water in the air. Sometimes fog can be so thick, it's hard to see anything.  It's San Francisco or London or a Stephen King story.

Here, the city disappears. Then the skyline  emerges, rising along the lake again.  It is beautiful, atmospheric, eerie.

Here is the statement from the National Weather Service for this morning,  May 6--

FOG IS WIDESPREAD ACROSS NORTHERN ILLINOIS AND 
NORTHWEST INDIANA THIS MORNING. SOME OF THE FOG 
IS DENSE WITH VISIBILITY UNDER ONE QUARTER OF A MILE...
ESPECIALLY IN LOWER LYING AREAS OR NEAR BODIES OF 
WATER.AREAS OF DENSE FOG WILL CONTINUE THROUGH 
9 OR 10 AM WITH GRADUAL IMPROVEMENT THROUGH NOON. 
EXERCISE CAUTION DURING THE REST OF THE MORNING COMMUTE...
PLANNING FOR POSSIBLE LONGER TRAVEL TIMES...AND 
BE PREPARED FOR LOW 
AND RAPID CHANGES IN VISIBILITY.

What causes fog?  Weather questions.com explains it this way--

Like clouds, fog is made up of condensed water droplets which are the result of the air being cooled to the point (actually, the dewpoint) where it can no longer hold all of the water vapor it contains.

For clouds, that cooling is almost always the result of rising of air, which cools from expansion. But for fog, which occurs next to the ground, there are usually other reasons for this cooling.

For instance, rain can cool and moisten the air near the surface until fog forms.

Or, as is more often the case, infrared cooling of a cloud-free, humid air mass at night can lead to fog formation - this is called "radiation fog". Radiation fog is most common in the fall, when nights get longer, air masses begin to cool, and land and water surfaces that have warmed up during the summer are still evaporating alot of water into the atmosphere.

Finally, a warm moist air mass blowing over a cold surface (usually snow or ice, or over a cold ocean surface) can also cause fog to form-this is called "advection fog".

Morning fog  dissipates  later in the day. As the air and ground warm up, the air temperature becomes warmer than the dew point temperature, causing the fog droplets to evaporate.

Fog is common here in the spring, as explained in this article in the Chicago Tribune. It is even more intense with the  arrival of warm gulf air, which may  bring temps in the 80's on Thursday.

Perhaps the most famous Chicago fog  happened on December 31, 1988-- the Fog Bowl, the  NFL playoff game between the Philadelphia Eagles and the Chicago Bears.

A dense fog rolled over Soldier Field during the 2nd quarter, cutting visibility to about 15–20 yards for the rest of the game. In spite of difficult conditions, the game continued and the Bears ended up winning the game 20–12.

You can watch the Fog Bowl again on You Tube.

 

 

 

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Filed under: seasons, weather

Tags: fog, Fog Bowl

Comments

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  • I noticed, coming in from the western suburbs back to the northern ones yesterday about noon that suddenly the temperature dropped and the fog became dense.

    Skilling says it is 69 at O'Hare and 78 in the southwest, but my WeatherBug is registering 58 at the moment.

  • In reply to jack:

    Thanks for reading and sharing your observations, Jack!

  • Thank you for an appropriately atmospheric treat of a post. The memories of the Fog Bowl and the fog-over-ice bring back another sporting memory for me: In May 1971, when the Blackhawks played Montreal in the Stanley Cup finals, it was so warm in Chicago Stadium (from weather and crowds) that fog was in the building. The Blackhawks lost by one goal. (Sigh!)

  • In reply to Margaret H. Laing:

    Great story! Thanks for reading and sharing!

  • In reply to Weather Girl:

    You're welcome. I hope it's not a factor this year!

  • In reply to Margaret H. Laing:

    That used to happen in Buffalo all the time (the fog, not the Stanley Cup).

  • Great post, fog is fascinating because it alters everything and your post did a great job explaining it all.

  • In reply to Kathy Mathews:

    Thank you so much, Kathy--I learned a lot, too :)

  • The comics synchronicity of the day.

  • Thanks for sharing, Jack!

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