We have entered the micro-season of “White Dew on Grass”. This is the first micro-season of the mini-season of White Dew. The other micro-seasons within White Dew are:
- White Dew on Grass (Sep 07 – Sep 11)
- The Wagtail Calls (Sep 12 – Sep 16)
- The Swallows Leave (Sep 17 – Sep 21)
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 explore how dew is formed and look into dew harvesting. Then, we will read some seasonal haiku by Issa, Basho, Saigyo, and Buson.
What Is Dew
“Dew” is the term we use to describe the condensation of water vapor in the form of small droplets on an object. Dew usually forms in the morning on objects that are close to the ground. The “dew point” is the phrase that we use to describe the environmental conditions that allow dew to form.
How Dew Is Formed
Dew appears on objects that are poor thermal conductors.(2) This is because these objects will quickly lose their heat. The loss of heat is usually a result of a loss of solar warmth. When these objects cool, they cool the air around them. This cooling allows the water vapor to condense into the water droplets on the surface of these objects.
Air temperature and humidity are very important for the formation of dew. Optimal conditions for dew formation include:
- Warn days
- Higher humidity
- Light winds
- Moisture in the soil, and
- Clear night skies that allow for cooling
Conditions that can disrupt the formation of dew include:
- High winds – High winds have the potential to mix air masses with different moisture contents.
- Cold temperatures – Once the temperature reaches 32 °F (0°C) the condensing water turns into frost instead of dew.
- Arid/dry climates – Regions that have low humidity are less likely to have enough moisture in the ground or air to create dew.
Uses of Dew
The collection of dew has the potential to bring water to places where other sources of water are lacking. For example, in the village of Kothara in the Kutch region of India, scientists are experimenting with a specially designed dew harvester. The harvester has condensation panels that allow for dew to form and then drip into a central channel. The central channel directs the collected water into a collection tank and then to a purification system. This dew harvester, which covers about 540 sq. meters (5,800 sq feet), has the potential to collect about 320 mm (12.5 inches) of rain and atmospheric water per year.(4)
Another example of dew harvesting comes from the Dalmation Coast of Croatia. Between 2003 and 2006 scientists used a few modified roof rain collectors, or “impluviums”, to collect dew. The annual collection amounts from this small test ranged from ⅓ of an inch (9.3 mm) to ¾ of an inch (20 mm).(5) As a result of these numbers, the scientists were then able to conclude that if they refurbishes about 1300 sq. meters (1400 sq. feet) of these impluviums they could collect about 14,000 Liters (369 Gallons) of dew water per year. This could provide a good amount of supplementary water to the region.
According to the World Kigo Database (WKD) “dew” is an autumn seasonal world. Dr. Gabi Greves explains that dew “has been used as a symbol of autumn in Japanese poetry since the Heian period. . . .Since it refers to something that loses its being when the sun starts shining, it is a symbol of the fleeting life itself. In Buddhism, death is just a step to another way of being, and the time spent with the ancestors is so much longer than the time spent here on this earth. Dewdrops are the perfect metaphor for the changes in the natural circle of all things, like the shells of cicadas.”(6) With this framing in mind, let us see how dew shows up in haiku.
the child unaware of the white dewdrops a Buddha (Translated by David Lanoue)
it's a dewdrop world surely it is... yes... but... (Translated by David Lanoue)
trembling, teetering now even more dew-like - lady flowers (Translated by Barnhill)
a chrysanthemum drops its dew, but when I pick it up: a brood bud (Translated by Barnhill)
dew trickles down: in it I would try to wash away the dust of the floating world (Translated by Barnhill)
A flash of lightning! The sound of dew Dripping down the bamboos (Translated by R. H. Blyth)
Blyth writes this about this haiku: “As Buson stands in the bamboo forest in the early morning, there is a flash of lightning; the whole of nature seems in a state of tension, the mind of the listener with it. At this moment of suspense, the drip-drip of dew falling through the bamboo grove is felt so deeply, it can hardly be called hearing.”(8)
A Haiku Invitation
This week’s haiku invitation is to write a haiku or senryu using “dew”. The WKD says that dew is an autumn kigo, so keep this in mind as you write.
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!
- “Dew”; National Geographic
- “Dew”; Wikipedia
- Jeff Haby, “The Forecasting Dew”; Weather.gov
- Dinesh C Sharma, “Indian scientists develop technology for harvesting water from dew”; DownToEarth
- M. Muselli, D. Beysens, M. Mileta, I. Milimouk; “Dew and rain water collection in the Dalmatian Coast, Croatia,” ScienceDirect
- “Dew (tsuyu)”; World Kigo Database
- “tsuyu dew”; WKD – Matsuo Basho Archives
- R.H Blyth; Haiku Vol III. Retrieved from Haiku Foundation Library
Issa’s haiku were retrieved from the World Kigo Database’s “dew” page. Matsuo Basho’s and Saigyo’s haiku were retrieved from WKD – Matsuo Basho Archives. Buson’s haiku was found in Haiku Vol. IIi By R.H. Blyth
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