Air pressure is a subject of fascination apart from its relationship to the complex phenomenon of Earth’s weather system. Our planet manifests multiple physical systems worthy of investigation—systems ranging from small to large and simple to complex. The subjects of air and air pressure are examples of systems which appear to become increasingly complex as we discover the interrelationships of multiple systems. Sub-systems interlock to form complex systems.
One example of a simple system begins with air. Upon study we discover simpler sub-systems: Air is composed of molecules of nitrogen (two atoms of nitrogen chemically linked) and molecules of oxygen (two atoms of oxygen chemically linked). Nitrogen and oxygen are two of eight diatomic elements. Even more simple is the system of individual atoms. Each atom of nitrogen or oxygen can be considered a system. Atoms are wonderful examples of fine-tuning and design, from the consistent forces holding their electrons to the nucleus, to the identical masses of each proton, neutron, and electron.
Our air blanket is held close to the earth’s surface by the force of gravity. If there were no gravity there would be no air clinging to the planet’s surface. In our atmosphere all of Earth’s weather occurs. The weather system would not exist without an atmosphere. Of course, virtually all earth life depends on the components of the atmosphere—oxygen for animal life and CO2 for plant life. The dynamic blanket of air must cling to the earth and be able to move, mix, and transport life sustaining water vapor from place to place. Moving air is termed wind. Dynamic connotes forceful, powerful, and energetic. Hundreds of physical requirements must be fulfilled and hundreds of processes must be completed successfully in order for human and other life to exist.
Changes in air pressure from one Earth location to another are a necessary pre-requisite for producing moving air. Air pressure varies according to temperature and altitude. Cooler air possesses higher pressure; warmer air possesses lower pressure. Several factors result in global temperature variability. The primary factor is varying solar radiation. When the sun’s rays strike Earth at a high angle near the equator, the earth receives more heat; it becomes warmer. In contrast when the sun’s rays strike the earth at a low angle at high latitudes, the planet receives less heat. We have contrasting temperatures—cold at the poles; warm at the equator.
Wind results from the tendency of higher pressure air to flow toward regions of lower pressure. Light winds result from adjacent areas with a moderate pressure difference. Strong winds result from substantial differences in pressure—there is a strong pressure gradient because strongly different pressure zones occur near each other.
Diagrams of Earth’s wind belts remind us of the importance of differences in air pressure existing from one location to another. Wind belts result from the tendency of air to flow from high to low pressure. A large portion of earth’s population exists in wind belts termed prevailing westerlies or northeast/southeast trade winds. Wind belts converge or diverge in their effort to equalize pressure conditions. In terms of our healthy, dynamic weather system, these effects are necessary. Absence of differences in pressure would result in the absence of wind, the absence of precipitation-producing storm systems and the absence of a mechanism for distributing life giving water where it is needed. It is not difficult to imagine that earth life would be very different if it would exist at all.
Looking back on my personal classroom teaching experience during weather units, we trust that after many years my former students may still relate the “wow factor” of our crushed can and vacuum pump demonstrations (5-11-17 post) to the importance of air pressure as that topic relates to the welfare and survival of life on this unique planet. Earth’s weather is a complex system for which success depends upon the effective working of many supporting sub-systems. Who could deny the supernatural design features of our weather system as well as thousands of other working systems enabling the existence of life on our Earth system?
Earth’s life sustaining weather system is a marvel of complexity and beauty. Many other systems yield their secrets of design and the supernatural intelligence of the designer, the Creator of All Things. As parents and teachers of both young people and adults, we must first discover for ourselves the sense of wonder at the many operating systems surrounding us.