Micro-Season: “Damp Earth Humid Heat” (2023)

July 28 to Aug 01 is the micro-season of “Damp Earth Humid Heat”.  This is the second micro-season of the season of Major Heat.  The micro-seasons within Major Heat are:

• The First Paulownia Fruit Ripen (Jul. 22 –  Jul. 27)
• Damp Earth Humid Heat (Jul 28 – Aug 01)
• Heavy Rain Showers  (Aug 02 – Aug 06)

These seasons were established in 1685 by Japanese astronomer Shibukawa Shunkai. While they are specific to Japan, you can use these seasons as a starting point for your exploration of the natural world.

To celebrate this season, we will learn about humidity and read haiku by Basho, Issa, Kerouac, and Shiki.

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Humidity

Humidity refers to the quantity of water vapor in the air. When the air contains a higher amount of water vapor, we describe it as having high humidity. Increased humidity poses a challenge for our bodies to cool down efficiently, as the sweat we produce cannot readily evaporate into the surrounding air.

Measuring Humidity

When scientists talk about humidity, three terms are often mentioned: absolute humidity, relative humidity, and dew point.

Absolute Humidity

Absolute Humidity is the actual amount of water vapor in the air. The higher the amount of water vapor, the higher the absolute humidity. Absolute humidity is measured in grams of water vapor per cubic meter volume of air.

Relative Humidity

Relative Humidity is the amount of water vapor in the air compared to the amount of water vapor that could be in the air, which is dependent on the temperature of the outside air.    

To explain this a little further, warm air can hold more water vapor than cold air.  So, given the same absolute humidity, the relative humidity would be higher on a cold day and then lower on a warm day.   The warm air has more capacity to hold the water.  

Relative humidity is measured as a percentage.

Dew Points

The dew point is the temperature at which the water vapor will turn into water droplets. The higher the dew point temperature, the more water vapor in the air.  Dew point is often used as a way to indicate how “muggy” it will feel when going outside. 

Typically, a dew point in the 50s feels comfortable. When the dew point reaches the 60s, it starts to be uncomfortable. While dewpoints in the 70s are considered quite uncomfortable and very humid. 

Although dew point and relative humidity are similar they are not the same thing.  The National Weather Service provides this explanation.

“While dewpoint gives one a quick idea of moisture content in the air, relative humidity does not since the humidity is relative to the air temperature. In other words, relative humidity cannot be determined from knowing the dewpoint alone, the actual air temperature must also be known. If the air is totally saturated at a particular level (e.g., the surface), then the dewpoint temperature is the same as the actual air temperature, and the relative humidity is 100 percent.”⁽²⁾

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Heat Index

The Heat Index, also known as the apparent temperature, “is what the temperature feels like to the human body when relative humidity is combined with the air temperature.”⁽⁴⁾  You can calculate the heat index by plugging your local the relative humidity level and the temperature into a complex mathematical formula, by using a heat index calculator, or by referencing the Heat Index chart.

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As you can see in the chart, Caution is advised when the heat index is as low as 80°F. When the heat index reaches between 90°F – 103°F, Extreme Caution is recommended and there is a possibility of heat stroke, heat cramps, or heat exhaustion with prolonged exposure or physical activity.  103°F – 124°F is considered the Danger level where heat cramps, heat exhaustion, and heat stroke is possible. 103°F – 124°F is Extreme Danger and heat stroke is highly likely.

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Seasonal Haiku

In this season, we are talking about the increased heat of the summer season and its impact.  Looking at The Five Hundred Essential Japanese Season Words as selected by Kenkichi Yamamoto, we can see relevant kigo appearing in the Season category and in the Humanity section. 

In the Season category, words like “heat”, “smoldering” and “burning” fit with this period.  In the Humanity category words like “cooling off” and “swimming” also fit.

In A Dictionary of Haiku by Jane Reichhold, our relevant kigo are found in the Celestial and Livelihood categories.  In Celestial, we have “heat”, “heat waves” and “hot days”.  In Livelihood, we have “swimming”, “sweat”, and “sleeping outdoors”.  

Interestingly, “humidity” is not listed as a kigo in these two sources or in the World Kigo Database. 

So now, with all this in mind, let’s read some haiku about hot and humid summer days.

Basho

a lake
the heat misses the clouds
on the peak 
(translated by Jane Reichhold)

withered grass— 
faint heat waves 
one or two inches high 
(translated by David Landis Barnhill)

in the cow shed, 
the dusky sound of mosquitoes: 
lingering summer heat. 
(translated by David Landis Barnhill)

pouring the hot day
into the sea– 
Mogami River 
(translated by Haruo Shirane) 

Issa 

back gate--
under the big hackberry tree
nobody cooling off 
(translated by David G. Lanoue)

back in the house
cooling off again...
moon in the window 
(translated by David G. Lanoue)

in heat shimmers
the holy man's
bare feet 
(translated by David G. Lanoue)

Kerouac

So humid you can't
    light matches, like
Living in a tank

Too hot to write
   haiku–crickets
and mosquitoes

Shiki

Oppressive heat–
My whirling mind
Listens to the peals of thunder
(retrieved from Terebess Asia Online)

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Haiku Invitation

This week’s haiku invitation is to write a haiku or senryu that references the hot and humid days of summer. 

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!  

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Thank You!

Resources:

1. “What is Humidity”; Scijinks NOAA
2. “Discussion on Humidity”; National Weather Service
3. “Humidity”; National Geographic
4. “Heat Index”; National Weather Service

Basho’s haiku was retrieved from Matsuo Bashō’s haiku poems in romanized Japanese with English translations. Issa’s haiku was retrieved from David G. Lanoue’s HaikuGuy.com.  Jack Kerouac’s haiku were retrieved from Book of Haikus.  Shiki’s haiku was retrieved from Terebess Asia Online.