Chapter 1

1. Chapter 1 Introduction to the Atmosphere

2. Weather Influences Our Lives a Great Deal. The United States likely has the greatest variety of weather of any country in the world. Severe weather events such as tornadoes, flash floods, and intense thunderstorms, as well as hurricanes and blizzards, are collectively more frequent and more damaging in the United States than in any other nation.

3. Few Aspects of Our Environment Influence Our Daily Lives Like Weather Beyond its direct impact on the lives of individuals, the weather has a strong effect on the word economy, by influencing agriculture, energy use, water resources, transportation, and industry. Weather clearly influences our lives a great deal. Yet it is also important to realize that people influence the atmosphere and its behavior as well. There are, and will be, significant political and scientific decisions to make involving these impacts.

4. A Typical Newspaper Weather Map Meteorology – the scientific study of the atmosphere and the phenomena of weather. Weather – the state of the atmosphere at a given time and place 1) Weather is constantly changing, day-to-day or even hour-to-hour 2) Weather is acted on by the combined effects of Earth’s motions and energy from the Sun. Climate – an aggregate of weather conditions, the sum of all statistical weather information that helps describe a place or region

5. Map Showing Percentage Chance of Sunshine in Different Areas The nature of both weather and climate is expressed in terms of the basic elements, those quantities or properties measured regularly. The most important elements are: air temperature, humidity, type and amount of cloudiness, type and amount of precipitation, air pressure, and speed and direction of the wind.

6. Costs of Weather Disasters in the United Sates Natural hazards are apart of living on Earth. Everyday they adversely affect millions of people worldwide and are responsible for staggering damages. Some, like earthquakes and volcanic eruptions, are geological in nature, but a greater number of hazards are related to the atmosphere. Occurrences of severe weather have a fascination that ordinary weather cannot provide. Hurricanes and tornadoes attract a great deal of attention as a single one of these events can cause billions of dollars in property damage, much human suffering, and many deaths. The four hurricanes that struck the U. S. in August and September 2004 caused more than $40 billion in damages and 152 deaths. Hurricane Katrina (2005) is estimated to have caused $130 billion in damages and more than 1,800 deaths.

7. Scientific Inquiry Science is based on the assumption that the natural world behaves in a consistent and predictable manner can be understood through careful and systematic study. The development of new scientific knowledge involves some basic logical processes that are universally accepted. Scientists collect facts through observation and measurement that serve as springboards for the development of scientific theories. The scientific method is a process used by scientists to answer questions about the natural world. The method involves the collection of facts, the development of a hypothesis, tests of the validity of the hypothesis, and the use of newly acquired information to accept, reject, or modify the hypothesis.

8. Automated Surface Observing System (AOSS) Observing the Atmosphere Scientific study of the atmosphere began in the seventeenth century as instruments were developed to measure different elements of the atmosphere. Galileo invented a type of thermometer in 1593, and in 1643 Torricelli built the first barometer. By 1661 Robert Boyle discovered the basic relationship between pressure and volume in a gas. During the eighteenth century, instruments were improved and standardized, and extensive data collection began.

9. High Altitude Observations Gathering data from ground-level sites only significantly limited an understanding of Earth’s atmosphere. Kites were first used to obtain data above Earth’s surface. In the late eighteenth century manned balloon flights were attempted in an effort to collect information. Today unmanned balloons play a significant role in the systematic study of the upper atmosphere. Modern weather balloons are equipped with radiosondes, lightweight packages of instruments fitted with radio transmitters that send back data on temperature, pressure, and relative humidity in the lower portions of the atmosphere. Helium Weather Balloon Radar and Satellites Other tools used to study the atmosphere include radar and satellites. Recent technological advances have greatly enhanced the value of weather radar for the purpose of storm detection, warning, and research. Satellites give meteorologist a “big picture” view of weather. Images from satellites allow scientists to study the distribution of clouds and the circulation patterns that they reveal. Additionally, they let scientists see the structure and determine the speed of weather systems over the oceans and other regions that are sparsely populated. Satellites also enable scientists to monitor storms from space, and measure and monitor variables such as winds, solar radiation, temperature, precipitation, and changes in atmospheric composition.

10. Earth; Viewed from Space Describing our Planet Earth can be divided into four independent parts that can be called spheres. They include: the geosphere – solid Earth; the atmosphere – gaseous envelope; the hydrosphere – water portion; and the biosphere – life. These spheres are not separated by well-defined boundaries. Each sphere is intertwined with all of the others, and these spheres can be thought of as being composed of numerous interrelated parts.

11. A Shoreline is an Interface between Two Parts of the Earth System; Land and Water The geosphere is the solid Earth. It extends from the surface to the center of the planet, a depth of about 6,400-km. It is the largest of the Earth’s four sphere. The geosphere can be divided into three principal regions: the core, the solid, dense center of Earth; the mantle, much less dense than the core; and the crust, the light, thin outer skin of the Earth. Soil a thin layer of material on Earth’s surface that supports the growth of plants, may be thought of as part of all four spheres. It is solid, so it is part of the geosphere; it contains organic matter, so it is part of the biosphere; and it is part of the hydrosphere and geosphere because soil is a product of weathering which involves air and water.

12. The Atmosphere Is only a Shallow Layer Compared to the Radius of the Solid Earth The atmosphere is a life-giving gaseous envelope that surround the Earth. Compared to the radius of the Earth (6,400-km), the atmosphere is very shallow. More than 99 percent of the atmosphere is within 30-km of Earth’s surface. The atmosphere not only provides the air we breathe, but also acts to protect us from the dangerous radiation from the Sun. The energy exchanges that continually occur between the atmosphere and Earth’s surface and between the atmosphere and space produce the effect we call weather.

13. Distribution of Earth’s Water The hydrosphere contains all the water that exists on this planet. The oceans account for 97 percent of all water, and covers 71 percent of Earth’s surface. Fresh water, although just a small fraction of the total amount, is vital to life on Earth. In addition, the movement of fresh water on Earth’s surface is responsible for creating many of the planet’s varied landforms.

14. Mt. St. Helens The biosphere includes all life on Earth. Most life, whether land- or water-based, occurs near Earth’s surface. In the oceans most life is concentrated in the sunlit surface waters. On land, tree roots and burrowing animals reach a few meters underground, while flying insects and birds reach a kilometer or so above the surface. While plants and animals depend on the physical environment for the basics of life they do more than just respond to the physical environment. Through countless interactions, life forms help maintain and alter the physical world around them.

15. The four spheres that make up Earth are not separate entities,but are highly interactive, forming a dynamic body that can be called the Earth system. A system can be any size group of interacting parts that form a complex whole. Most natural systems are driven by sources of energy that move mater and/or energy from one place to another. Closed systems are systems where matter and energy move through the system but the total amount of matter and energy never changes. When matter and energy can flow into and out of a system that system is described as an open system. A weather system like a hurricane is an example of an open system. Systems are controlled by feedback mechanisms. Negative feedback mechanisms work to maintain the system as it is, while a positive feedback mechanism encourage or enhance change in the system.

16. The Carbon Cycle The Earth system has a nearly endless array of subsystems in which matter is recycled over and over again.. Examples of recycling subsystems include: the water cycle, in which water continually moves from the atmosphere to Earth’s surface and back; the rock cycle, in which, by a variety of processes, rock is changed from igneous to metamorphic and/or sedimentary, which can then be recycled as igneous rock; and the carbon cycle, where carbon is moved through the four spheres of the Earth system. The different recycling systems can interact with each other. The common boundary where different parts of a system come in contact and interact is known as an interface. Two sources of energy that power the Earth system are: (1) the Sun, which drives the external processes that occur in the atmosphere, hydrosphere, and at Earth’s surface, and (2) heat from Earth’s interior that power the internal processes that produce volcanoes, earthquakes, and mountains.

17. Composition of the Atmosphere Air is a mixture of many discrete gases, and its composition varies from time to time and place to place. After water vapor, dust, and other variable components are removed, two gases, nitrogen and oxygen, make up 99 percent of clean, dry air. While carbon dioxide accounts for about 0.02387 percent of the air, it is an efficient absorber of energy emitted or reflected from Earth, and the recent increase (over the past 100 years) of this gas in the atmosphere is likely warming the lower atmosphere and could trigger global climate change.

18. Satellite Image of a Dust Storm and Human-Generated Air Pollution The variable components of air include water vapor, dust particles, and ozone. Water vapor can absorb heat given off by Earth. When water vapor changes state it absorbs or releases energy. In the atmosphere, water vapor transport heat from one place to another, a source of energy that drives many storms. Tiny solid and liquid particles are called aerosols and are important because these often invisible particles act as surfaces on which water can condense and are also absorber and reflectors of incoming solar radiation. Ozone, a form of oxygen that combines three oxygen atoms into each molecule (O3), is a gas concentrated in the 10- to 50-km height range in the atmosphere that absorbs the potentially harmful ultraviolet radiation from the Sun.

19. Changes in the Antarctic Ozone Hole Over the past half century (50 years) the insertion of chlorofluorocarbons (CFCs) into the atmosphere has threaten the ozone layer in Earth’s atmosphere. Ozone is critical to life on Earth as it protects all life on Earth’s surface from overexposure to ultraviolet radiation from the Sun. Ozone concentrations take a sharp drop over Antarctica during the Southern Hemisphere spring (September and October). Ozone thinning, although less severe than over the South Pole, also occurs neat the North Pole during spring and early summer. The Montreal Protocol represents a positive international response to the ozone problem.

20. Atmospheric Pressure Changes with Altitude No sharp boundary to the upper atmosphere exists. The atmosphere simply thins until there are too few gas molecules to detect. The change that occurs in atmospheric pressure depicts the vertical extent of the atmosphere. One-half of the atmosphere lies below an altitude of 5.6-km (3.5 miles) and 90 percent lies below 16-km (10 miles).

21. Thermal Structure of the Atmosphere Using temperature as the basis, the atmosp0here is divided into four layers: The troposphere – closest to Earth’s surface. Generally, temperature decreases with altitude. Essentially all important weather phenomena occur here. The troposphere is thicker at the tropics and thinner in the polar regions. The stratosphere – above the troposphere, the temperature remains constant until an altitude of about 20-km and then begins to increase sharply due to the absorption of ultraviolet radiation The mesosphere – temperatures again decrease with an increase in altitude. The thermosphere – temperatures increase with an increase in altitude.

22. Height of the Tropopause Varies with Latitude Based on composition, the atmosphere can be divided into two layers: the homosphere and the heterosphere. The homosphere extends from Earth’s surface to an altitude of of about 80-km (50 miles). The makeup of the air is uniform in terms of the proportions of it component gases (Fig. 1-21, page 20). The heterosphere located above 80-km altitude is not uniform. The gases are arranged into four roughly spherical shells, each with a distinctive composition. In order: lowest shell is dominated by molecular nitrogen (N2), then a shell of atomic oxygen (O), followed by a layer of dominated by helium (He) atoms, and finally a regions consisting of hydrogen (H) atoms.

23. The Aurora Borealis (Northern Lights) Occurring in the altitude range between 80- and 400-km is an electrically charged layer of the atmosphere known as the ionosphere. Molecules of nitrogen and atoms of oxygen are readily ionized (gain an electric charge) as they absorb high energy, shortwave solar energy. Three layers of varying ion density make up the ionosphere. The auroras ( aurora borealis and aurora australis) occur within the ionosphere. Auroras form as clouds of protons and electrons ejected fro the Sun during solar-flare activity enter the atmosphere near Earth’s magnetic poles and energize the atoms of oxygen and molecules of nitrogen, causing the to emit light.