Some musings from a Weather by Day reader

Kevin Chisholm of Barrachois, N.S. shared these musings with me early this week.

Hi Cindy

I had an old Friend, Charlie Johnston, born in 1913, who had a saying:

“The best time to burn slash (“forest trash”, like tree tops and limbs) is on the decline of the full moon.” I told this “observation” to another Friend who had a strong science based background, and he basically dismissed it as “An Old Farmer’s Tale”… an anecdotal observation… “Where is the evidence?”

My guess is that Charlie’s observation could indeed have a valid scientific basis. My reasoning is as follows:

1: The full moon is usually associated with clear skies, and cooler night time temperatures.

2: The cooler night time temperatures could cause heavy dews, and lowering of the relative humidity or the air mass

3: During the days, there would thus be less cloud cover, lower relative humidities, and greater

sunlight heating

4: The slash could indeed become drier, and easier to burn, in the period when the full moon was in decline. With all the historical Weather Data available, it might be possible to analyze it to show my “Science Based Friend” the following evidence:

1: Relative Humidities are generally lower in the period when the full moon is in decline.

2: Sunlight hours are generally higher when the full moon is in decline, leading to generally higher average temperatures and lower average daytime Relative Humidities.

3: The slightly higher average daily temperatures could lead to relatively more “convective breezes”. 4: These conditions could lead to better “drying conditions for forest slash.

If this was the case, then there could be enough “Science Based Evidence” to reasonably conclude that the belief of Charlie Johnston (and probably his Grandmother!): “The best time to burn slash is on the decline of the Full Moon” was indeed a “scientifically valid observation”.