I am writing a series of essays on the difficult scientific questions from the Hebrew Scriptures Book of Job to assess how much we have learned over the past 5,000 years.
Job lived somewhere east of the Euphrates River about 3000 BC, or maybe even before the Great Deluge, 25,000 years ago. He posed a series of very difficult questions, at least for the time; but my main point is that many are still difficult.
Question: Do you know the treasures of snow or hail? Do you know the watercourses? Or the way of thunder? Does it rain where no men live? To keep the earth moist and to cause flowers and plants to grow and bloom? Who makes the rain?
Where does the dew originate? Is there water underground? What is ice? And where does frost come from? Can you send lightning? What do you know about clouds? What is drought? (Job 38: 22-38)
We can now mostly answer all of these questions about the weather, yet we are still mostly uncertain about the physics of lightning. We still have imperfect understanding of snowflakes and ice.
Man has been studying the weather, loosely called meteorology, since ancient times to better grow crops and for ocean navigation. The Greeks began recording observations, made more formal by Aristotle in 350 BC. The hope was to predict or forecast the weather.
The Koreans developed instruments to measure rainfall in the 1400s. Modern instruments have made all of the difference. Temperature, pressure, wind measurements and humidity are the variables that are measured by a thermometer, barometer, anemometer and hygrometer, respectively. Professional weather stations also might include air quality sensors (carbon monoxide, carbon dioxide, methane, ozone, dust and smoke), ceilometer (cloud ceiling), falling precipitation sensor, flood sensor, lightning sensor, microphone (explosions, sonic booms, thunder), pyranometer/pyrheliometer/spectroradiometer (IR/Vis/UV photodiodes), rain gauge/snow gauge, scintillation counter (background radiation, fallout, radon), seismometer (earthquakes and tremors), transmissometer (visibility), and a GPS clock for data logging.
Upper air data are of crucial importance for weather forecasting. The most widely used technique is launches of radiosondes. Supplementing the radiosondes is a network of aircraft collection organized by the World Meteorological Organization. Weather satellites, radars and ocean buoys are also important. (This paragraph mostly from Wikipedia.)
Earth’s atmosphere, rising approximately 300 miles, held in place by gravity and in layers, is where our weather exists. At the equator the air is the hottest, while toward the poles the air gets cooler. The hottest place on earth is the Sahara Desert. The highest average annual temperature is registered in Dalul (Ethiopia), in a depression located 116 meters (390 feet) under the sea level: 94 degrees Fahrenheit. At Verhojansk (Siberia), the temperature reached minus-94 degrees Fahrenheit. The atmosphere protects us from the sun and most falling objects but makes re-entry of spaceships challenging.
Nephology is the science of clouds. Clouds are floating collections of water, ice or other particles. Clouds are named according to their height, shape or content.
The dew point is the temperature to which air must be cooled to become saturated with water vapor. When further cooled, the airborne water vapor will condense to form liquid water (dew). Clouds can appear colored according to light scatter or refraction or cloud particle content.
Rain occurs as clouds rise and cool, so their dew point is reached. Very small raindrops can be spherical but are usually not spherical and can flatten as they fall. Most raindrops contain some dust. The terminal velocity of large drops is faster than small drops (20 mph vs 4.5 mph); some raindrops have been noted to be as large as one-third of an inch.
Most rainwater originates in the oceans, drawn up without salt. Frozen rain is called hail in thunderstorms, created by the cooling effect of a very fast updraft, and called ice pellets in cold weather. Hail stones form in layers and are brought to earth by gravity. Typical hail can be up to 3 inches and obviously damaging. A mountain in Kenya averages 50 days of hail per year, with occasional sizes more than 2 pounds and approximately 8 inches in diameter. Hail suppression by cloud seeding is often not successful.
Snowflakes indeed are a treasure. The advent of the microscope has revealed their artistic beauty. Lens were known to magnify by the Babylonians 4,000 years ago, but the modern microscope dates from the 1200s and in modern form in the 1600s (Galileo and Drebbel). Snowflakes form around a nucleus and water drops add as the flake falls and freezes; indeed, it is rare to find a duplicate. They can be beautiful and often nearly symmetric mathematically in form and in shape.
We still do not know the exact physics of snowflake formation. Snowflakes pilling up is called snow. Ice is, of course, just frozen water, but as the Job question indicates, it is more complex than “that.” Ice expands and becomes less dense at it freezes.
Ice has multiple chemical compositions and bonding structures (at least 18) for reasons we do not understand. We still do NOT know why ice is slippery, having a lower coefficient of friction than expected.
Permanent ice is an important feature of both of Earth’s poles. Glaciers cover roughly 10% of Earth’s land and are still under study, not fully understood. Lakes often freeze over to a depth of several feet, often strong enough to hold modern vehicles. Lake ice often breaks up in a single day in the spring.
Wind is the movement of gases or air from high pressure to low pressure. Wind is affected by temperature and the spin of the earth. We now can measure wind density, direction, power and speed. We do not exactly yet know what starts the movement of the wind, however.
Wind is both useful and a potential menace. Wind speeds have been measured up to 250 mph. Rotating wind and weather is called a tornado and can be destructive. We still do not know exactly how tornadoes form, but the rotation is caused by rising warm air meeting cool air in a cumulonimbus cloud. Tornado wind speeds are usually mid-range for storms and travel at most 10 to 20 miles.
Only recently have we begun to understand thunder, lightning and fulminology, and even so, lightning is still wrapped in mystery. In fact, despite our recent advances, we really know very little about lightning. There are approximately 1.5 billion lightning flashes per year around the world. Most are in the atmosphere and not seen by us, but sometimes they are heard. Roughly 70% of lightning strikes occur in the tropics.
Basically, charged particles, usually of hail or ice, are created as air and gas moves up very rapidly in thunder clouds. Once charged particles are separated by at least 10 feet, they can discharge. But in addition, the ground under thunder clouds is also charged by mechanisms not yet understood, and so the cloud can discharge to the ground. This is the lightning we usually see. We have no idea what sparks a lightning strike or how it begins. But we do know that lightning can carry enormous amounts of energy, much of it as light, heat and electricity, up to gigajoules.
Benjamin Franklin first discovered lightning to be electricity (1752) and invented the lightning rod to protect buildings from strike damage by grounding the charge, hopefully harmlessly. But lightning also carries X-rays, nuclear plasma (including anti-matter), magnetic fields and gamma rays. We think the light is created by stripping of electrons in the path of the strike, but for the rest we still have no idea how they are created, except that they exist.
We think the sound of lightning (we call it thunder) is either from the electron stripping or the rapid expansion of gas and air along the route of the strike to create a shock wave. Since sound travels at about 1,100 feet per second, much slower than light, you can estimate the distance of the visible lightning strike by the timing of the sound.
I have a personal story about lightning: An uncle was killed in 1940 by a lightning strike. He was sitting indoors at a window with a niece on each side, one sitting on his knee, all watching a thunderstorm. A lightning strike, witnessed by two other adults, came down the nearby kitchen stove chimney in the shape of a ball, turned a corner in the kitchen, doing no damage, then struck through him to go out the window, killing him instantly. Neither niece was harmed except for one small burn mark.
Only about 10% of humans are killed when struck by lightning but can have residual damage.
The force of lightning has impressed mankind through the ages, thinking it to either be a god or from the gods. The most famous of the lightning gods are Zeus and Thor, I suppose.
Except in the laboratory, we still cannot control or understand the physics of lightning, but don’t give up.