- Education and Science
Climate and Weather: The Current Heat Wave in the United States
Yes, there is, indeed, a heat wave in the United States. Temperature records are being set even as this article is being written, and long range forecasts say it will continue for several more weeks.
So what the heck is going on? First a warmer-than-normal winter and now a warmer-than-normal summer; is it cyclical as some believe, or is it further fodder for those who believe in global warming?
Any such discussion must first start with an explanation of what weather is and what causes weather.
DEFINITIONS FIRST, THEN EXPLANATIONS
Weather is defined as the atmospheric conditions at a given time in a given place. Climate is the atmospheric conditions for a place over a long period of time.
For example, the weather in Olympia, Washington on the 4th of July was 72 degrees Fahrenheit, a gentle wind of 5 mph and clear skies. The climate for Olympia is West Coast Marine, which means that Olympia is greatly affected by the Pacific Ocean with close to fifty inches of rain annually, moderate temperatures winter and summer, and moderate humidity.
SO WHAT CAUSES WEATHER?
Weather is the product of uneven heating by the sun on the Earth’s surface. Heat is transported both vertically and horizontally within our atmosphere, and whenever there is air transporting heat from higher to lower temperatures there must also be a return flow of air in the opposite direction. This process is called an atmospheric cell and there are three major cells at work constantly as we go about our daily lives. Those three cells are the Hadley Cell, the Ferrel Cell, and the Polar Cell.
Discovered by George Hadley in the 18th Century, this refers to the rising of heat above the Equator and then the motion of that heat toward the poles. When that energy reaches the 30th Parallel, north and south, the energy sinks down to the surface and then circulates back toward the equator.
If you look at a map of the Earth you will note that most of the world’s deserts fall within this 30 degree area. That is not by accident.
We have William Ferrel to thank for this discovery during the early 19th Century. What he found was that the Ferrel Cell acts sort of like a ball bearing between the Polar Cells and the Hadley Cells, bringing warm air toward the Poles from the 30th Parallels and returning colder air from the Poles to the subtropics.
In conjunction with the theories of George Hadley, it was determined that the air movement within the Ferrel Cell will almost always move west to east in the Northern Hemisphere and from east to west in the Southern Hemisphere between the 30th and 60th Parallels.
Like the Hadley Cells, the Polar Cells are a closed loop. Air is warm enough to rise at the 60th Parallels and then move toward the Poles. Once it reaches the Poles it will cool off and drop down to the surface of the Earth, where it will close the loop by returning to the 60th Parallels, and then the process starts all over again.
BUT THERE IS SO MUCH MORE
Jet Streams are fast flowing currents of air that circulate between 23,000-39.000 feet above sea level. Think in terms of a raging river of air constantly moving around the Earth. The strongest of the jet streams is the Polar Jet Stream. These rivers of air circulate in a general west-to-east direction, but they can easily meander in a northerly or southerly direction for a few hundred miles and then change direction. It all depends on the rising and falling of warm air and where that rise and fall occurs.
EL NINO AND LA NINA
Recent studies have found a phenomenon occurring in the eastern Pacific Ocean near the Equator. The El Nino phenomenon is an increase in the surface temperature of the ocean in this area, usually by at least 0.5 degree Celsius.
The La Nina is the opposite occurrence in the same region, usually a drop in surface temperature of between 3-5 degrees Celsius. Scientists cannot agree on the cause of these anomalies but there is no doubt that they affect the weather, most notably between the 30th and 60th Parallels, and each lasts between one to two years.
PUT IT ALL TOGETHER AND YOU GET…….
Well, yes, what do we get? We get constantly moving air of different temperatures, and a constant battle between warm and cool air. We have weather systems constantly moving around the Earth, each interacting in a delicate and complicated dance.
WHICH BRINGS US TO….
Well, it brings us to the current heat wave in the United States. If this air aloft is constantly moving, and systems normally move from west to east, how come this high pressure system is parked over much of the United States and is not moving?
It is unusual but for certain it has happened in the past and will happen again in the future, and in truth scientists are not certain why it is happening right now; nor are they certain why the recently completed winter was warmer than normal. For whatever reason, and chances are it is because of several reasons, the high pressure system is not moving; the jet stream has taken a detour and any low-pressure systems that could change things are being diverted north or south of the United States.
Remember that it takes several days to several weeks for a weather pattern to change; thus the prediction that this heat wave could continue for awhile longer.
ONE MAN’S LOOK BACK IN TIME
I can tell you with all certainty that the climate has changed in the Pacific Northwest during my lifetime. I do not need scientific data to know that; I have simply observed a drastic change in the climate over the past fifty years. Spring and summer are much cooler than they were when I was a youngster and winters are milder. Of course we will have the occasional year when those statements are not true, but overall I can say without a doubt that there has been a major shift in this area.
The question then becomes why? Here is where the major debate begins, a debate that can be heard around the world, from the man on the street to the lawmakers and scientific community. Are we seeing the effects of global warming? Has the hole in the ozone layer caused this drastic change in weather? Is this just cyclical in nature and will the cycle run its course and then a new cycle begin?
I have no desire to debate any of this! If scientists, with all of their schooling and expertise, cannot agree, then my input seems a bit futile in nature.
One thing that is not debated is the fact that all weather is interconnected. It is a constant game of cause and effect being played out above us daily. Think in terms of the Butterfly Effect on steroids. What happens at the Equator will eventually affect other parts of the world. The three circulation cells and the jet streams guarantee that fact.
Warmer air at the Equator will bring about a change in weather somewhere else. Colder air at the Poles will also bring about a change. Toss the Water Cycle into the argument and one has to ask what deforestation in the Amazon is doing to the world’s weather and climates? How are the melting ice caps affecting the weather? And on and on we go!
We are talking about an intricate balance, one that is greatly affected by any number of factors; it has been that way since the beginning of time and it will continue, unabated, well beyond our time here on Earth. As stewards of this planet let us hope that we find definitive answers to many of these questions sooner rather than later.
2012 William D. Holland (aka billybuc)
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