Air and Breathing
The atmosphere of the earth is a thin, layered collection of gases, water vapor and particles. Most living creatures live in the atmosphere. The troposphere is the surface layer of air that absorbs visible sunlight. Heating, cooling, and water evaporation in the troposphere are expressed as weather.
The weight of air around an object exerts pressure. At sea-level the weight of air molecules above each square inch is about 14.7 pounds. Air pressure varies with temperature and weather patterns are described in terms of low pressure fronts interacting with higher pressure fronts.
The air thins as you ascend above the Earth air pressure and temperature drops. The stratosphere begins at about 12 miles altitude at the equator; about 5 miles at the poles. Solar ultraviolet radiation is absorbed by oxygen and ozone. The "ozone layer" is about 30 miles high; 90% is located within 10 miles above the Earth's surface. The atmosphere thins progressively in the mesosphere, the outer layer that extend to 53 miles altitude. Atmospheric gases eventually disappear into relatively empty, cold space.
Stratospheric ozone absorbs ultraviolet sunlight providing heat and protection for living creatures in the lower atmosphere. At the Earth's surface, ozone from human industry is toxic. In the 20th century, it became obvious that gases created by human activity changed the chemical composition of the troposphere and stratosphere with negative impacts on human survival. Large ozone holes appeared over the Antarctic and the Arctic Polar regions. Smaller areas of ozone depletion were recorded over other, more-populated regions of the Earth. Increases in surface UV-B radiation have been recorded wherever stratospheric ozone was depleted. A scientific consensus was reached that human-produced chemicals were responsible for ozone depletion. Combinations of volatile chemicals containing chlorine, fluorine, bromine, carbon, and hydrogen were responsible; carbon tetrachloride, and methyl chloroform were used in refrigeration, air conditioning, and as solvents. Halons, which contain carbon, bromine, fluorine, and chlorine were also implicated. An international agreement was achieved so that many governments outlawed CFCs, halons, carbon tetrachloride, and methyl chloroform.
Global Warming - Climate Changes
Progressive increases in the emission of greenhouse gases that warm the planet should be treated as a global emergency. Increased heat changes all environments. Humans are dying in increasing numbers when heat waves overwhelm them. Much attention has been paid to environmental pollution and the effects of specific toxic and carcinogenic molecules in our environments. Revelations of major alarming atmospheric changes - the greenhouse effect and ozone holes - have served to remind us of our destructive effect overall on planet Earth. We suffer individually and collectively from our own pollution.
Developments in the media made "green" the slogan for action to limit the adverse effects of air pollution. The media often suggested that this is a relatively new consensus that there is an environmental crisis. They excused people who have ignored the effect of greenhouse gases on climates global warming over the past 40 years. Some know what is really going on out there, but most people do not know or know but deny the obvious for selfish reasons.
The model of of atmospheric dynamics that has emerged from a high tech,
multidisciplinary study of the planet is complex. Important players in
atmospheric dynamics are:
Glass covering greenhouses admits light and heat energy but blocks some of the infrared heat energy that is radiated back. The green house stays warmer than the external environment. In the atmosphere, a similar effect occurs. Global warming means that the earth retains more of the sun's heat over time. The increased heating of greenhouse gases is reduced by increased reflection of the suns' energy reaching the earth by clouds and particle pollution in the atmosphere. Without particle pollution, the heating effects would be greater. The greenhouse effect from increased carbon dioxide, nitrous oxide and methane during the 20th century is the most conspicuous man-made change. The reduction in forest biomass and the exposure of ocean plankton to increase UV radiation are also concerns.
Heat drives weather and increased heat means increased turbulence in the atmosphere. The consequences vary with the distribution of this extra heat and its effect on ocean and air circulation patterns. We can accept paradoxical and extreme weather results as the extra heat makes weather systems more turbulent and changes air and water circulation patterns.
World Meteorological Organization/United Nations Environment Programme report, Scientific Assessment of Ozone Depletion: 1998 (WMO Global Ozone Research and Monitoring Project-Report No. 44, Geneva, 1999).