How do you do it? This is the main question
I receive after precisely predicting weather occurrences months
in advance such as the rain which ended this summer's drought.
Of course I cannot reveal all of my secrets but one of the
major steps to follow is to predict the opposite of what local
weathermen are predicting!
As air is heated it expands and will hold
more moisture. Cooler air, on the other hand, holds less
moisture. If the moisture content of the air is unchanged
by weather changes, the air becomes "heavier"
or more moisture?saturated as it cools, because it is capable
of holding less and less as it cools. At some temperature
it will not be able to hold any more. Humidity is then 100%.
That temperature is called the "dew point."
If the dew point is 35 degrees the humidity
will be 100% at 35 degrees. If the temperature drops much
lower, the result will be fog. Is not fog, like clouds,
tiny droplets of water? The more moisture in the air, the
more heat will be retained, trapped. The dryer the air,
the greater the heat loss. The kiss of death is a night
that stars are shining real bright ? no humidity or clouds
to block the heat ? and no wind. The higher the dew point
the less chances of frost. The lower the dew point, the
greater the chances. Seldom will you get frost with a dew
point of 45 or higher. When the dew point is down in the
20's you are in for a frost unless daytime high was above
Why is there frost on the grass before
the tomato plants were killed? When the earth is experiencing
rapid radiational cooling, the heat is rising very fast.
Therefore, it is warmer 40 feet off the ground than at ground
level, and the bottom few feet are really dramatic. Just
barely above the ground is the coldest. A thermometer can
read 33?34 degrees at 4 feet high, yet there can be frost
on the grass. If one is placed at grass level and another
in between at four feet the temperature can be 33?34 degrees.
At two feet it can be 31 degrees, and at grass level it
will be 29?30 degrees. There can actually be a degree drop
Because the temperature can differ at various
heights off the ground, the National Weather Service places
its recording instruments at exactly four feet high. We
would do well to do the same so as to have a common frame
of reference. Just remember that on a dry, cold night, the
ground can be as much as 4 to 5 degrees colder (or as little
as 0 or 1 degree) depending on cloud cover, dew point and
One of the keys to predicting the first
frost is the moon. Before you laugh this idea off as lunacy
consider the following.
Because at the time of a new or a full
moon both sun and moon are lined up to bring about a maximum
gravitational pull giving rise to the highest tides, these
periods have frequently been presumed to have a particular
influence on what to plant and when to plant it. Root and
tuberous crops are supposed to perform more satisfactorily
when planted on a waning moon, diminishing light; while
flowering, fruiting and foliage crops are presumed to produce
higher yields when planted under a waning moon, increasing
light. Although no experimental proof of these benefits
has been recorded, even if there were some such influence,
so many different considerations are involved in planting
that such a schedule of planting would be impossible to
follow without considerable difficulty in practice.
However, the moon does have at least one
valid, well?documented effect on the weather effect on the
weather which might be considered in relation to the planting
and culture of vegetables. Considerable heat is reflected
by the moon from the sun to the earth's upper atmosphere
during the nights when the moon is full. Most of this heat
is dissipated and serves to evaporate a haze or to thin
heavy cloud formations which at times hold heat near the
earth's surface. Clearing the sky, as a full moon frequently
tends to do, allows heat to be lost from the earth by radiation.
Late spring and early fall frosts are therefore of more
frequent occurrence, on any given date when the moon is
Dryer times are generally immediately preceding
or during a full moon or just before a new moon. Perhaps
the tides have something to do with the quantity of water
that is evaporated into the air during a new or full moon
and subsequently precipitated. Dryer times mean frosty times.
Once moisture comes in, only if all it does is to increase
dew points, further critical temperatures will usually not
occur until there is some new mechanism to bring drier air
back in again. Critical minimum temperatures is not only
a function of how cold the air is, but how dry the air is
and to a lesser effect how moist the soils are. I will stand
by the November 22 prediction. So don't laugh at the moon.
Perhaps if planting in relation to the signs of the zodiac
and the astrology were forgotten, and possible associations
between the various phases of the low night temperatures
and rainfall were observed for a period of time, the moon
information on the calendar might become of considerable
value in certain sections of the country. Even though you
may no longer be romantically inclined, it may be worthwhile
to keep up with the changes in spring and fall moons.