Micro-Season: “Thick Fog Blankets The Sky”

We have entered the micro-season of “Thick Fog Blankets the Sky”.  This is the third micro-season of the mini-season of First Autumn.  The micro-seasons within First Autumn are:

These seasons were established in 1685 by Japanese astronomer Shibuka Shunkai and are specific to Japan. However, just because the calendar focuses on Japan doesn’t mean it isn’t applicable to others.  No matter where you live you can use these seasons as a starting point for your personal exploration of the world around you. 

As a way to celebrate this season, we will investigate what causes fog and how to classify the different types of fog.  Then we will read poetry from Masaoka Shiki, Kobayashi Issa, Matsuo Bashō, Yosa Buson, and Carl Sandburg.

What Is Fog?

Fog is usually described as a low-lying cloud. Much like clouds, fog is made of suspended water droplets.  However, unlike clouds, fog usually forms close to local water sources and doesn’t necessarily travel long distances.  

Fog can be formed from either the condensation of salt water or fresh water.  A fog that appears near bodies of salt water is called Sea Fog, haar, or sea fret.(1)

Is It Fog Or Mist?

One way to tell the difference between fog and mist is through the reduction in visibility.  Fog reduces visibility to less than 3,281 feet or 1,000 meters.  Mist is less dense than fog and does not significantly obscure visibility.  When there is a mist in the air your visibility range is greater than 1,000 meters.(2)

How Is Fog Formed?

Fog is formed when water vapor condenses and then forms water droplets suspended in the air. National Geographic explains, “In order for fog to form, dust or some kind of air pollution needs to be in the air. Water vapor condenses around these microscopic solid particles. Sea fog . . . is formed as water vapor condenses around bits of salt.”(3) It also needs to be very humid for fog to form.  

Bay Bridge and Golden Gate Bridge and San Francisco in fog-Photo Credit: Brocken Inaglory
Bay Bridge and Golden Gate Bridge and San Francisco in fog-Photo Credit: Brocken Inaglory

Is All Fog The Same?

We have already mentioned that fog can be made up of either freshwater or saltwater particles.  However, fog is also divided into seven different categories based on the way it is created and its location.  The following descriptions are adapted from classification given by the National Weather Service.(4,5)

Advection Fog:

Advection fog forms when moist air moves over a cold surface.  This process creates a cooling of the surface air to below its dew-point temperature which makes fog. Advection fog can occur over both water and land. 

Radiation fog (ground or valley fog):

Rapid heat loss from the earth’s surface produces this type of fog. The best condition to have radiation fog is when it had rained the previous night. Rain helps to moisten up the soil and create higher dew points. This makes it easier for the air to become saturated and form fog. However, the winds must be light less than 15 mph to prevent moist air and dry air from mixing.

Precipitation Fog:

This type of fog forms when rain is falling through the cold air. Precipitation fog is common with warm fronts. But it can also occur with cold fronts if the front is not moving too fast. Cold air, which is dry near the surface of the earth, evaporates the rain and causes the dew point to rise. This saturation forms the fog.

Steam Fog or Arctic Sea Smoke.

In northern latitudes, steam fog forms when water vapor is added to cold air and then condenses into fog. It is commonly seen as wisps of vapor emanating from the surface of the water. This fog is most common near lakes and rivers during autumn and early winter, when waters are still warm and colder air masses prevail. Under these conditions, the visibility is often 3/16 miles (300 meters) or less. 

Upslope Fog: 

This type of fog occurs when sloping terrain lifts the air, cooling it adiabatically to its dew point and saturation. Adiabatically is the scientific term used to describe the process where sinking air warms and rising air cools. The rising air cools significantly enough to meet up with the dew point temperature and then creates fog. Upslope fog is usually seen on the top of the mountains.

Freezing Fog:

Freezing fog occurs when the temperature falls to 32°F (0°C) or below. This fog produces drizzle and these tiny droplets freeze when they come into contact with an object. 

Ice Fog:

This type of fog is only seen in the polar and arctic regions. Temperatures at 14 F (-10°C) are too cold for the air to contain super-cooled water droplets so it forms small tiny ice crystals.

Fog Density

Fog is also separated into three different density categories based on the visibility limits. These categories are:

  • Regular Fog – visibility below 1,000 m (1,100 yards) – mainly affects aircraft.
  • Thick fog – visibility 50-200 m (55 – 220 yards) – dangerous for road traffic.
  • Dense fog – visibility below 50 m (55 yards) – seriously disrupts all forms of transport.(6)
Fog over the road: Photo by Markus Spiske on Pexels.com
Fog over the road: Photo by Markus Spiske

Poems For This Season

The World Kigo Database tells us that although fog may happen at any time of the year, fog is considered an autumn or winter kigo. Below are a few examples of fog-themed haiku by Masaoka Shiki, Kobayashi Issa, Matsuo Bashō, and Yosa Buson.


Ah, if I come back,
him that passes before me
is nothing but fog.
(Translated by Adam Critchley)


evening fog -
the horse remembers
the holes in the bridge

(Translated by Dr. Gabi Greve)


clouds of fog
quickly doing their best to show
one hundred scenes 
(Translated by  Jane Reichhold)


morning fog:
painted in a picture –
dream people passing.
(Source:  David Coomler)
In the morning fog
a city of one thousand eaves — 
market noises
(Translated by Allan Persinger)

“Fog” by Carl Sandburg

Although “Fog” by Carl Sandburg is not exactly a haiku, I found this short poem very appropriate for the season.

The fog comes
on little cat feet.

It sits looking
over harbor and city
on silent haunches
and then moves on.

An Haiku Invitation:

Last week, I offered an invitation to use the micro-season theme as inspiration for your own poetry. The responses were so great I thought I would continue this haiku invitation.

So, if you are up for the challenge, write your own haiku or senryu using Fog as inspiration. Share your haiku in the comments below, or post on your own page and link back to this post.

I can’t wait to read what you write!


  1. “Fog”; Wikipedia 
  2. “What is the difference between mist, fog, and haze?”; Met Office
  3. “Fog”; National Geographic Society
  4. “Fog Guide”; National Weather Service
  5. “Fog Types”; National Weather Service PDF
  6. “Fog, Mist, Haze, and More”; World Kigo Database

The poetry for today’s post was pulled from a variety of sources:

Want to support our work? Visit the Naturalist Weekly bookstore and browse our curated lists of books of poetry and haiku. Or pick up a gift card that can be used throughout the store.   

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30 thoughts on “Micro-Season: “Thick Fog Blankets The Sky”

Add yours

  1. I am no Bashō, but I know how to have fun:

    dogs wander through fog
    they still poop on your trimmed lawn
    uproot your roses
    Arriving hours late
    Amanda blamed the dense fog.
    She may have been right.
    Five years post chemo
    the cure fogs my memory.
    Who are you again?
    on the southern coast
    he’d hoped to catch a cool fog.
    Late again, he mist.

    1. Very nice! I really like the last one. A little haiku humor in there. The Five years past is also a very clever use of fog. Well done and thanks for sharing!!

  2. Nice work as always, Mark, and educational as well. I can’t help but be reminded of my time spent in Oregon and how the coastal fog cloaked Heceta Head Lighthouse in a soundless veil, lending a peculiar mysterious and forlorn aspect to it.. I really enjoyed the haiku you’ve included, and I definitely recall Sandburg’s poem from my high school days (those “little cat feet” are so descriptive). Here are my haiku offerings regarding fog/mist:


    Misty river bank
    I can hear the water cry
    Through its mournful veil


    Autumn ground mists rise
    Earth gives up its ghosts as moon
    Summons spirits home


    Early morning mist
    Mother cloud comes home to nest
    Earth is safe and warm


    Early morning mist
    In the green konara copse
    Forest holds its breath

    1. Hi Mike, Nice to see you again and what a collection of haiku! I think #31 is my favorite out of this list. Thanks so much for sharing these!

    1. I hope the heat breaks soon! We had a mild week but the heat returned today. There was also a fair amount of fog around the mountains this morning. Speaking of brain fog, did you see Tnkrr’s haiku? All about brain fog. I hope all is well and thanks for the comment!

  3. I enjoyed the Basho Haiku the most. Once again, I am out of sync with these microseasons. I set out this morning to see what the season is here. It’s definitely not fog, since we are in a drought. “Red leaves reach down” inspired by a sassafras branch I passed by on my morning walk.

    1. What a wonderful seasonal description. I actually noticed a couple of maple leaves that were starting to turn this weekend. Seems much too soon. Although, I don’t think that is really the case. Up here in the Northeast there was a blanket of fog around the mountains on Saturday morning. So timely! Thanks for the comment and I hope all is well!

    1. Hi Cindy, the fog around SF seems very intense. I can see how it might not be that enjoyable. But I am glad you can enjoy the haiku! Thanks for the comment and I hope all is well.

  4. I like the way fog clouds the known world into a shroud of mystery. Suddenly my pasture has the air of a suspense novel. 🙂

    I general like fog, but freezing fog is dangerous around here. It can create some very bad freeway accidents.

    1. Hi Melanie, There is something mysterious about a fog covered landscape. Especially in the early evening or at night.
      I don’t think I have ever experienced freezing fog. I can definitely see how it could be dangerous. Thanks for the comment and I hope all is well on the west coast!

  5. Who knew there was so much to know about FOG! – me clearly really enjoyed it and so glad you are now doing your own haiku prompts love it, I will definitely have a go 🙂

    1. I am so glad that you enjoyed the post and I am very excited that you are going to take up the invitation to write a haiku. I am looking forward to see what you come up with!

  6. Pingback: Fog Tonight | Hourglass Poetry
    1. Hi Nancy, Thanks for adding your work this season! I really like the imagery here. I haven’t lived in a city for a long time so I almost forget what it is like to have the fog roll in and have it weaves its ways through the buildings.

      1. Well, Mark, living in a small city like I do, that is bounded by Lake Erie on one side and has a river running through it, tends to cause more than our share of fog as it rolls up the river and from the lake. The fog coming off the river often extends “tentacles” of fog in different directions.

        Have a great weekend.

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