Atmosphere, climate and weather

Atmospheric gases scatter blue light more than other wavelengths, creating a blue halo when seen from space.

A view of Earth's troposphere from an airplane.

Lightning is an atmospheric discharge of electricityaccompanied by thunder, which typically occurs duringthunderstorms, and sometimes during volcanic eruptionsor dust storms.^[14]

The atmosphere of the Earth serves as a key factor in sustaining the planetary ecosystem. The thin layer of gases that envelops the Earth is held in place by the planet's gravity. Dry air consists of 78% nitrogen, 21% oxygen, 1% argon and other inert gases, such as carbon dioxide. The remaining gases are often referred to as trace gases,^[15] among which are the greenhouse gases such as water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Filtered air includes trace amounts of many otherchemical compounds. Air also contains a variable amount of water vapor andsuspensions of water droplets and ice crystals seen as clouds. Many natural substances may be present in tiny amounts in an unfiltered air sample, including dust,pollen and spores, sea spray, volcanic ash, and meteoroids. Various industrialpollutants also may be present, such as chlorine (elementary or in compounds), fluorinecompounds, elemental mercury, and sulphur compounds such as sulphur dioxide[SO₂].

The ozone layer of the Earth's atmosphere plays an important role in depleting the amount of ultraviolet (UV) radiation that reaches the surface. As DNA is readily damaged by UV light, this serves to protect life at the surface. The atmosphere also retains heat during the night, thereby reducing the daily temperature extremes.               

Principal layers

Earth's atmosphere can be divided into five main layers. These layers are mainly determined by whether temperature increases or decreases with altitude. From highest to lowest, these layers are:

• Exosphere: The outermost layer of Earth's atmosphere extends from the exobase upward, mainly composed of hydrogen and helium.
• Thermosphere: The top of the thermosphere is the bottom of the exosphere, called the exobase. Its height varies with solar activity and ranges from about 350–800 km (220–500 mi; 1,100,000–2,600,000 ft). The International Space Station orbits in this layer, between 320 and 380 km (200 and 240 mi).
• Mesosphere: The mesosphere extends from the stratopause to 80–85 km (50–53 mi; 260,000–280,000 ft). It is the layer where most meteors burn up upon entering the atmosphere.
• Stratosphere: The stratosphere extends from the tropopause to about 51 km (32 mi; 170,000 ft). The stratopause, which is the boundary between the stratosphere and mesosphere, typically is at 50 to 55 km (31 to 34 mi; 160,000 to 180,000 ft).
• Troposphere: The troposphere begins at the surface and extends to between 7 km (23,000 ft) at the poles and 17 km (56,000 ft) at the equator, with some variation due to weather. The troposphere is mostly heated by transfer of energy from the surface, so on average the lowest part of the troposphere is warmest and temperature decreases with altitude. The tropopause is the boundary between the troposphere and stratosphere.

Other layers

Within the five principal layers determined by temperature are several layers determined by other properties.

• The ozone layer is contained within the stratosphere. It is mainly located in the lower portion of the stratosphere from about 15–35 km (9.3–22 mi; 49,000–110,000 ft), though the thickness varies seasonally and geographically. About 90% of the ozone in our atmosphere is contained in the stratosphere.
• The ionosphere, the part of the atmosphere that is ionized by solar radiation, stretches from 50 to 1,000 km (31 to 620 mi; 160,000 to 3,300,000 ft) and typically overlaps both the exosphere and the thermosphere. It forms the inner edge of the magnetosphere.
• The homosphere and heterosphere: The homosphere includes the troposphere, stratosphere, and mesosphere. The upper part of the heterosphere is composed almost completely of hydrogen, the lightest element.

• The planetary boundary layer is the part of the troposphere that is nearest the Earth's surface and is directly affected by it, mainly throughturbulent diffusion.

         

Natural Environment

The natural environment encompasses all living and non-living things occurring naturally on Earth or some region thereof. It is an environment that encompasses the interaction of all living species.^[1] The concept of the natural environment can be distinguished by components:

• Complete ecological units that function as natural systems without massivehuman intervention, including all vegetation, microorganisms, soil, rocks,atmosphere and natural phenomena that occur within their boundaries.
  • Universal natural resources and physical phenomena that lack clear-cut boundaries, such as air, water, and climate, as well as energy, radiation,electric charge, and magnetism, not originating from human activity.
  The natural environment is contrasted with the built environment, which comprises the areas and components that are strongly influenced by humans. A geographical area is regarded as a natural environment.

  Water on Earth                                             

  
  
  An ocean is a major body of saline water, and a component of the hydrosphere. Approximately 71% of the Earth's surface (an area of some 362 million square kilometers) is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas. More than half of this area is over 3,000 meters (9,800 ft) deep. Average oceanic salinity is around 35 parts per thousand (ppt) (3.5%), and nearly all seawater has a salinity in the range of 30 to 38 ppt. Though generally recognized as several 'separate' oceans, these waters comprise one global, interconnected body of salt water often referred to as the World Ocean or global ocean.^[7][8] This concept of a global ocean as a continuous body of water with relatively free interchange among its parts is of fundamental importance tooceanography.^[9] The major oceanic divisions are defined in part by the continents, variousarchipelagos, and other criteria: these divisions are (in descending order of size) thePacific Ocean, the Atlantic Ocean, the Indian Ocean, the Southern Ocean and the Arctic Ocean.

  [edit]Rivers                                                  A river is a naturalwatercourse,^[10] usuallyfreshwater, flowing toward anocean, a lake, a sea or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be termed by several other names, including stream, creek and brook. In the United States a river is generally classified as a watercourse more than 60 feet (18 metres) wide. The water in a river is usually in a channel, made up of a stream bed between banks. In larger rivers there is also a wider floodplain shaped by flood-waters over-topping the channel. Flood plains may be very wide in relation to the size of the river channel. Rivers are a part of thehydrological cycle. Water within a river is generally collected from precipitationthrough surface runoff, groundwater recharge, springs, and the release of water stored in glaciers and snowpacks.A river is a naturalwatercourse,^[10] usuallyfreshwater, flowing toward anocean, a lake, a sea or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be termed by several other names, including stream, creek and brook. In the United States a river is generally classified as a watercourse more than 60 feet (18 metres) wide. The water in a river is usually in a channel, made up of a stream bed between banks. In larger rivers there is also a wider floodplain shaped by flood-waters over-topping the channel. Flood plains may be very wide in relation to the size of the river channel. Rivers are a part of thehydrological cycle. Water within a river is generally collected from precipitationthrough surface runoff, groundwater recharge, springs, and the release of water stored in glaciers and snowpacks.A river is a naturalwatercourse,^[10] usuallyfreshwater, flowing toward anocean, a lake, a sea or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be termed by several other names, including stream, creek and brook. In the United States a river is generally classified as a watercourse more than 60 feet (18 metres) wide. The water in a river is usually in a channel, made up of a stream bed between banks. In larger rivers there is also a wider floodplain shaped by flood-waters over-topping the channel. Flood plains may be very wide in relation to the size of the river channel. Rivers are a part of thehydrological cycle. Water within a river is generally collected from precipitationthrough surface runoff, groundwater recharge, springs, and the release of water stored in glaciers and snowpacks.

bodies introductionof nature

This issue of Body & Society was assembled to extend the interest in the embodied nature of people's experiences in, and of, the physical world. It thus seeks to develop further the emergent sociology of the body that has provided extensive insight into the embodied character of human experience. Such a sociology has, though, dealt less systematically with the various social practices that are involved in being in, or passing through, nature, the countryside, the outdoors, landscape or wilderness. These practices reflect the apparently enhanced `culture of nature' in many contemporary societies. In particular, we are concerned with various embodied performances. The various articles consider: how is the body implicated in, and reproduced through, the diverse social practices happening within `nature'? Why is the body, and its physical capital, developed by practices thought to be beneficial because of the `natural' setting for such practices? In what form do these practices `in nature' come to be part of the reflexivity about the body, as the self and identity are increasingly matters of deliberation, negotiation 

Your Own Backyard

This is not a cliché. Most back yards are teeming with wildlife of some sort. As a city dweller, I never cease to marvel at the fine variety of life in my yard. Spend time in your yard as you take meals, and see how many kinds of bird, insect, plant, etc. that you see.
If you keep a perfectly manicured lawn, with only one kind of grass (need a field guide to help you learn your lawn?), you can make your yard more attractive to wildlife. Hang a birdfeeder. Add a birdbath. Try piling up some old hedge clippings to make a brush pile. Dig in the soil.
 
You might consider starting a ‘succession corner.’ Choose a small area. Don’t mow, spray or treat the area. Watch. The grass will grow long, weeds will grow, and young trees might sprout. Different insects will arrive. After a few years, you might start a second succession area beside the first, and see how much faster succession takes place. For more backyard ideas, check out MacBeth's Opinion (a small bookstore, in association with Amazon.com), including a "Swallows and Amazons" page! 

Charlotte Mason's Observations

Charlotte Mason (1842-1923) was a British educator and an observant woman. As a teacher, she spent much of her life watching children learn, and drawing, from her observations, many of the same conclusions we home educators draw today as we watch our own children learn. Nature study was a “must” for Charlotte’s students, and for those she influenced in their homes. She believed that children should be outside with a parent for 4-6 hours per day when they are young, and that older children (12 and up) should have at least one full afternoon a week devoted to outside activities. Meals should be taken out of doors, when possible. “Never,” she writes, “be within doors when you can rightly be without.” Today, at Charlotte Mason College (now part of St. Martin's College), the study of ‘outdoor education’ can earn you a master’s degree. Indeed, outdoor educations centers such as Frost Valley in NY, and PEEC in Pennsylvania, Hemlock Overlook in Virginia, Eagle Bluff in Minnesota, and many others, are popular ways that public schools bring a taste of the outdoors to their pupils. Ah, but as home-schooling families, we can make everyday an outdoor educational experience…

Charlotte’s image of the nature walk included the mother sitting on a large blanket and sending the kids off to find what they can find. They would return with their finds, or describe what they had seen to their waiting mother. This might work well for you. Others may use a blanket as a “home base.” I cannot help but walk with my children and find things. I don’t want to miss anything on our nature outings, and my enthusiasm is contagious. Either way is fine, I believe. 

The kids love to find natural objects and learn from them what they can. They keep notebooks, recording their interesting discoveries. They make connections when they read about something they have seen on a nature walk. They develop a strong, respectful relationship with life and its Creator. Nature study becomes the basis for the study of all other sciences—geology, biology, chemistry, physics, and astronomy can all be observed in nature. 

INTRODUCTION: THE NATURE OF SCIENCE AND BIOLOGY

Biology literally means "the study of life". Biology is such a broad field, covering the minute workings of chemical machines inside our cells, to broad scale concepts of ecosystems and global climate change. Biologists study intimate details of the human brain, the composition of our genes, and even the functioning of our reproductive system. Biologists recently all but completed the deciphering of the human genome, the sequence of deoxyribonucleic acid (DNA) bases that may determine much of our innate capabilities and predispositions to certain forms of behavior and illnesses. DNA sequences have played major roles in criminal cases (O.J. Simpson, as well as the reversal of death penalties for many wrongfully convicted individuals), as well as the impeachment of President Clinton (the stain at least did not lie). We are bombarded with headlines about possible health risks from favorite foods (Chinese, Mexican, hamburgers, etc.) as well as the potential benefits of eating other foods such as cooked tomatoes. Informercials tout the benefits of metabolism-adjusting drugs for weight loss. Many Americans are turning to herbal remedies to ease arthritis pain, improve memory, as well as improve our moods.