Weather and Climate
WEATHER is the condition of the atmosphere over a given spot on earth at a particular instant of time. CLIMATE is the effect of weather conditions on an area over a long period of time. In other words, weather is to climate as the experience of one day is to a lifetime.
Types of weather include rain, snow, sleet, hail, thunderstorms, tornadoes, hurricanes, fog, etc. The roots of weather events lie in the reaction of the air to the motion of the sun, to the rotation of the earth about its axis, to the distribution of continents and oceans, and to large mountain ranges, as well as many other factors. Most basic are temperature, air pressure, moisture, and wind. Also involved are ocean currents, jet streams, and land elevation.
Climate is based on the average weather statistics for an area and includes the amount of sun and cloud coverage, how much rain and snow an area has, the high and low temperatures, humidity, and the direction and strength of winds in the area. Daily weather continually fluctuates around the climate average. Over the years, extra cold and extra warm winters will tend to cancel each other out and be part of the overall average of a region’s weather.
The earth is divided into zones of climate by latitudes, imaginary lines drawn around the globe. The equator is the center line which runs around the biggest part of the earth. The areas just north and just south of the equator are called the torrid zones, which are always hot. Just north and just south of the two torrid zones are two temperate zones, which are medium in temperature. At the North Pole and at the South Pole are two areas called the frigid zones, which are always cold.
The term “climate” means “inclination” in Greek, referring to the inclination of the earth’s surface with respect to the sun’s rays. This shows how early in history the sun’s control of life on earth was recognized. As the earth spins on its axis and moves around the sun, it is sometimes at a very different angle when receiving the sun’s rays. For this reason, the amount of sunlight falling on the earth is constantly changing, as the position of the earth and its angle toward the sun change. This gives the earth its four seasons: spring, summer, autumn, and winter.
The angle of sunlight in the temperate zones between the poles and the equator changes greatly, causing a corresponding wide variation in the weather from season to season. The amount of sunlight that reaches the equator and the poles does not change as much during the year, so the weather of those places does not change very much either.
The moisture in the air and the amount of rain that falls determines whether an area will have an arid (dry) or humid (moist) climate. Three more factors that affect the climate of a place are how close to the ocean it is, what ocean currents flow near it, and how high it is above sea level. There are ocean currents that bring warm water from the tropic regions to the polar regions, and currents that bring cold water from the polar regions to the tropic regions. Countries that lie near these ocean currents have their climate affected by them, becoming either warmer or colder.
Distance from the ocean is important because the sun heats the land much faster than it does the ocean, and the land loses its heat at night much faster than the ocean. This is why places far inland have extremes of climate. For example, Kansas City has temperatures of more than 100 degrees in summer and temperatures below 0 in winter. But the climate of coastal cities is much more even. For example, San Diego ranges from 50 degrees in winter to 90 degrees in summer.
In places high above sea level, the air is colder. Even in the hot tropics, the tops of mountains are often covered with snow. For instance, the climate in the valleys of the Andes Mountains in South America is a hot, tropical jungle, but at the top of the mountains it is freezing cold.
Winds are also important to climate. Some winds move in definite routes. The winds that come from cold polar regions bring cold air with them, and so they cool the areas they pass through. Warm that winds come from the tropic regions will warm the air in places they pass through.
Did You Know…?
Jet streams are fast-moving currents of air high in the atmosphere. (When I was a kid and heard about jet streams, I mistakenly thought that the contrails of jet planes were affecting the weather! By the way, contrail is short for condensation trail. These are formed when water vapor from the exhaust of jet airplanes condenses into ice crystals at high altitudes.)
The Earth’s Eight Major Climate Zones
Equatorial - warm and wet (South America, Central America, Africa, South Pacific Islands)
Tropical - dry and rainy seasons (Africa, South America)
Oceanic - four seasons; winter, spring, summer, fall (North America, Greenland, British Isles)
Desert - hardly any rain (Africa, Arabia, Australia)
Monsoon - six months of heavy rain (Asia)
Continental - freezing winter, hot summer, brief spring and fall (Europe, North America)
Mediterranean - mild winter, warm summer, mild spring and fall (Italy, Spain, Greece)
Polar - freezing winter and cold summer (Arctic, Antarctica)
Northern Chile, most likely the driest place on earth, has spots where there has been no recorded rain in over 400 years! Mt. Waialeale on the island of Kauai, Hawaii, is the wettest place on earth, where it rains 250 days a year, averaging 460 inches (38 feet) of rain each year! The hottest climate is tropical East Africa, where the average annual temperature is 94 degrees F. The coldest climate is Antarctica, where the South Pole’s average temperature is 70 degrees below zero.
Climate and Man
Climate effects the way people live, eat, dress, work, and how healthy they are. Hot climates make it difficult for people to work hard. Cold climates make it hard for people to think well, although they will have plenty of energy for hard work. Too much dampness or too much dryness, or too much heat or cold, are bad for health. A temperate climate seems to be best.
Sailors, formers, hunters, and fishermen have always studied the weather because their work depends on it. They learned to predict changes by watching clouds, observing plants and animals, and noting body aches and pains. To further understand the weather, scientists invented instruments to measure temperature (thermometer), pressure (barometer), humidity (hygrometer), sunshine (heliograph), and wind speed (anemometer).
Atmospheric science is the branch of physics concerned with studying the air and understanding the processes taking place in the atmosphere. Meteorologists are scientists who study the weather. (Ben Franklin was America’s first meteorologist.) Climatologists study weather patterns over the years. Rapid advances in the knowledge of atmospheric science have been made since the 1940’s, due in part to increased understanding of the physical processes, expanded observing networks, and development of instruments to measure the atmosphere.
Today, meteorologists and climatologists use many different high-tech instruments. In fact, the effort to predict weather was one of the initial reasons for developing computers and satellites. Satellites send back pictures of clouds and record infrared radiation to determine temperature and humidity. Weather satellites have been especially successful at detecting and following the movement of hurricanes. Meteorologists also collect information from land stations, ships and buoys, and special aircraft. All of this data is fed into computers. Meteorologists then analyze the information to make forecasts, or predictions, of what the weather will be.
However, in spite of all these fancy weather instruments providing detailed technical data, weather forecasts are not always correct. Meteorologists can forecast weather accurately only a few days in advance. Any longer than this, and weather prediction becomes very uncertain for several reasons. Weather is the result of a great number of variables or controlling factors, as explained at the beginning of this article. Weather may also be sensitive to other conditions which can never be known exactly. As the number of variables in any scientific endeavor increases, the results become less predictable. These multiple and often unknown variables also rule out any comprehensive mathematical formula by which the weather can be exactly calculated.
Finally, weather is ruled by what scientists call unpredictable chaos. According to chaos theory, very small environmental factors can eventually result in large-scale differences in weather patterns. You may have heard about the law of magnified results, popularly known as the “butterfly effect.” According to this theory, the flapping of a butterfly’s wings in the Amazon rainforest may set in motion a chain of events that later results in a Midwest tornado. For these reasons, precise weather forecasting is impossible. Consequently, there is no way to predict next week’s weather, not to mention future climate changes.
The Greenhouse Effect and Global Warming
During the day, the sun’s heat is absorbed by the earth. At night, this heat is radiated back into the atmosphere. The gases in the atmosphere (water vapor, carbon dioxide, methane, and ozone) act as an insulating blanket, preventing this heat from radiating into space. This process is called the greenhouse effect. Without it, earth would be a frigid place where life could not exist.
The earth’s increasing population and accompanying activities (exhaling, burning fuels, and cutting down forests) has resulted in more carbon dioxide being put in the air than there used to be. While the total of all carbon dioxide caused by human activity is only 3% of the carbon dioxide produced by natural processes, the concentration of carbon dioxide in the air has nevertheless been rising steadily over the last 50-70 years.
We know that carbon dioxide is a participant in the greenhouse effect that warms the planet. Some think if the concentration of carbon dioxide in the air were much greater, that this would make the earth too warm. But there are other gases which participate in the greenhouse effect as well. It is not known exactly what concentration of each, if any, is most significant. Other gases may actually cancel out the effects of too much carbon dioxide, or other interrelated elements may counterbalance each other to maintain our current climate.
Consequently, it does not necessarily follow that increased carbon dioxide will result in global warming. In fact, there has not been a corresponding increase in the temperature of the earth. Recorded temperatures fluctuate up and down quite a bit, with some years warmer than others. But even while the amount of carbon dioxide in the air has increased steadily, the average temperature of the earth has not changed in the past 50-70 years. So the majority of atmospheric scientists do not consider global warming to be a major problem, despite what the media reports.
Ozone is a greenhouse gas that helps keep the earth warm and also protects us against harmful ultraviolet radiation. It has long been known that the “ozone hole” is a seasonal phenomenon that occurs naturally in the polar region due to global atmospheric circulation. Centered directly over Antarctica, it occurs only four months out of the year (August to November). Although the hole has grown slightly larger in recent years, the concentration of ozone in the ozone layer over Antarctica during the rest of the year (November to August) has not changed. Thus, the “ozone hole” effect is actually rather inconsequential.
Every year in late December, a southward moving current warms the Pacific Ocean off the coast of Peru and Ecuador. About every three to seven years, it makes the ocean warmer than normal. This warm water adds extra heat and moisture to the atmosphere, starting a chain reaction of weather disturbances around the world, generally causing winters to be warmer and wetter than average. The opposite effect can be seen in La Nina, when the ocean current is cooler than usual.
Exploring Creation with Physical Science, by Dr. Jay L. Wile.
National Audubon Society First Field Guide: Weather, by Jonathan D. W. Kahl.
The Weather Atlas, by Keith Lye.
Weather and the Bible, by Donald B. DeYoung.
The Weather Book (USA Today), by Jack Williams.
Weather and Climate (Young Discoverers), by Barbara Taylor.
Weather (DK Eyewitness Explorers), by John Farndon.
www.noaa.gov (National Oceanic and Atmospheric Administration: an incredibly informative site with interactive learning on weather, climate, oceans, satellites, and much more.)
www.weather.com (The Weather Channel: lots of info on weather and how it affects your life.)
www.wxdude.com (The Weather Dude: weather education site especially for kids, parents and teachers, featuring features musical meteorology pages.)
www.wildwildweather.com (Dan's Wild, Wild Weather Page: an interactive weather page for kids between 6 and 16 years old, and their parents and teachers.)
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These pages are a continuous work in progress.