On 2/5/16 3:48 PM, Steve Willner wrote:
In article ,
R Kym Horsell writes:
Comparing times of new moon
versus full moon shows a statistically relevant difference of
in preciptation of a few percent.

Can you cite a source? I confess to some skepticism, but if the
effect is real, my first thought would be biology rather than
physics.



Lunar Phase Affects Rainfall

http://www.reportingclimatescience.c...-rainfall.html


Abstract

Classical tidal theory predicts that the lunar gravitational
semidiurnal tide (L2) should induce perturbations in relative
humidity (RH). Adiabatic expansion in divergent flow in advance of
the L2 pressure minimum cools the air and reduces its saturation
vapor pressure, thereby increasing the rate of condensation in
saturated air parcels and causing the relative humidity (RH) of
unsaturated parcels to rise. Here we detect a statistically
significant L2 signature in precipitation rate (P) in a 15 year,
eight times daily, global precipitation data set acquired in the
Tropical Rainfall Measuring Mission. Consistent with tidal theory and
with the notion that L2 modulates P mainly by perturbing RH, P varies
out of phase with pressure, and it increases at a rate of about 10%
per 1% increase in RH. These measurements thus provide a measure of
the sensitivity of P to planetary-scale changes in RH. Analysis of
solar semidiurnal (S2) tidal statistics yields similar results.

Citation

Rainfall variations induced by the lunar gravitational atmospheric
tide and their implications for the relationship between tropical
rainfall and humidity by Tsubasa Kohyama John (Michael) Wallace
published in Geophysical Research Letters, DOI: 10.1002/2015GL067342


Their new paper is the first to show that the moon’s gravitational
tug also puts a slight damper on the rain.

When the moon is overhead, its gravity causes Earth’s atmosphere to
bulge toward it, so the pressure or weight of the atmosphere on that
side of the planet goes up. Higher pressure increases the temperature
of air parcels below. Since warmer air can hold more moisture, the
same air parcels are now farther from their moisture capacity.


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