This collection of topics, a brief view of life, could be used to teach an adolescent the basics about life.
Nature has many cycles. Each day has the sun up about half of the time, giving its light (important to all plants) and heat (important to all animals), and sun down the rest of the time, when its light and heat has been lost. The daily cycle is important; some animals sleep at night allowing the body to rest and the brain to adjust its memories, while other animals sleep during the day and are active during the night when it is more difficult to be caught and eaten.
There is a monthly cycle driven by the tides caused by the moon and sun. This rise and fall of the oceans is important for life along the shores as the animals and plants adjust to the changes in water depth, perhaps even coming out of the water sometimes or being under water sometimes. Women also have a monthly cycle that controls when they are more likely or less likely to be able to begin a baby.
There is a yearly cycle of seasons driven by the motion of the tilted earth around the sun, where the angle toward the sun enables more energy from the sun to raise the temperature of the soil and water while the angle away from the sun provides less energy so lower temperatures result. This yearly cycle has a big impact on animals and plants, where a cold winter drives many animals and plants to either hibernate (like bears in a den) or go dormant (like trees that lose all their leaves) or migrate to where it remains warm enough during the winter (like any birds). For many animals, the yearly cycle also drives when and where their babies are born.
The yearly cycle is also critical to farmers who must plant new crops in the spring when the conditions are right for new growth while there must be enough time for the crop to mature for harvest in the fall before the conditions get too cold for continued growth. Some people depend on an appreciation of the natural cycles.
There are even longer cycles in the oceans where for several decades an ocean will usually be warmer while in the subsequent decades that ocean will usually be cooler. These cycles in ocean temperatures will affect the weather around the world. For example, parts of the Pacific Ocean follow about a 60-year cycle, where about 30 years will be generally warmer while the other 30 years will be cooler. These ocean cycles affect the weather around the world, where for example much the United States the 1930's and the 1990's were much warmer while the 1960's were much cooler.
There appear to be even longer cycles but the records of weather over such a span of time are not precise. It appears about 1000 years ago the world was warmer than now, and also about 2000 years ago the world was also warm but an exact comparison is not possible, while about 500 years ago the world was cooler than now.
Beyond that, the earth goes through periodic ice ages. The last one ended about 10000 years ago. These are found in the geological record. In that record, the earth’s atmosphere can also be determined. There have been times in the far distant past when levels of carbon dioxide were much higher than now.
Some claim the world's current temperatures are so warm now as to be cause for alarm about carbon dioxide but those making such claims cannot back them up against the findings the world has been both warmer and cooler in the past, with levels of carbon dioxide also higher in the past than now.
References: on Wikipedia: ENSO, Ice Age
created - December 2011
last change - 12/17/2011
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