John Wheeler / Forum News Service
It seems simple enough to hold a thermometer out in the sun in order to get the temperature “in the sun.” But this idea is all wrong. Air isn’t heated up very much by sunlight. The rays pass right through. Air warms up in sunlight mainly because the sun’s rays heat the ground and that heat then rises up into the air via conduction and convection. A thermometer bulb in the sun will heat up dramatically past the ambient air temperature because it is a solid object and is warmed directly by the sun’s rays.
With a full month of summer remaining, it might well be unpopular to bring up the topic of winter weather. Nevertheless, I find myself wondering what sort of winter will come our way. Last winter was one of the mildest in Fargo Moorhead history. Snowfall, for the fourth consecutive winter, was below average. Our recent run of relatively mild and snow-less probably means an average sort of winter would likely be taken as cold and snowy by most people.
Along the Red River, between the Fargo water plant and Lindenwood Park, there is a stand of willow shrubbery that has been there as long as I can remember. During most of the past 25 years, these willows have grown to 3-5 feet high when not being completely flooded as they grow right on the riverbank. Last year and this year, the absence of summer flooding has apparently provided an opportunity for these shrubs to get very healthy because they have grown to well over 12 feet high. They managed to survive repeated floods but are now flourishing in this summer’s drought.
Most of us have seen those mysterious, silent flashes of light from an almost indeterminate direction, seen only at night. Most people call it heat lightning.
Evapotranspiration is the water evaporated from the ground back to the atmosphere both as transpiration from the leaves of plants and also as direct evaporation from open water and soil. The amount of water evaporated changes from day to day based on cloud cover, wind, relative humidity, temperature and other influences. On a sunny day this time of year, an average of approximately one-third of an inch of moisture is evaporated in a day. On a cloudy day that amount may be a tenth of an inch or less while on a hot, sunny day it could be more than half an inch.
The dry conditions this summer are likely to get worse rather than better. There have been fewer storms this year. It rains here and there, but general rainfall has been rare. Many people have remarked that “the storms always go around us,” and some have asked why this is.
The shrinking of the summertime Arctic Ice cap in recent decades has left me wondering when the last time the Arctic was ice free. It turns out this is a hard question to answer due to the fact that Arctic sea ice undergoes a little melting every summer from top (weather) and bottom (unfrozen ocean) which leaves a poor record. The most accepted theory is that the North Pole has been capped in ice continuously or nearly continuously for 2.7 million years, since the beginning of the present Wisconsonian ice age.
The Dog Days of Summer are here. Ancient Romans referred to this stretch from late July through late August as the “dog days” because of Sirius, the Dog Star. Astronomers in many ancient cultures, including early Egyptians, Greeks and Romans, noticed the correlation between the presence of Sirius and the latter days of the summer when the heat is hard to escape.
The last time it was 100 degrees in Fargo Moorhead was five years ago today. Prior to that, there were two days in the 100s in the summer of 2006, and those are the three days with century mark temperatures in Fargo Moorhead in this century.
We live in a windy place. The Great Plains, in general, is windy because there is very little surface terrain to slow the wind down. Also, here in the Northern Plains, the Polar Jet Stream is usually nearby and so we have a near-constant barrage of varying low and high pressure systems which keeps the air pressure in a state of flux.