Final PDF to printer CHAPTER 2 Energy and Matter in the Atmosphere ALMOST ALL NATURAL SYSTEMS on Earth derive their energy from the Sun, but not all areas receive the same amount of sunlight. Instead, the amount of energy reaching Earth’s surface varies from region to region, from season to season, and from hour to hour. The interaction of energy with the Earth’s atmosphere and surface determines the climate, weather, and habitability of an area. 02.00.a2 Namibia, Africa 02.00.a3 Philippines Sunlight warms the The Sun rises and sets land and oceans, which each day, except in some in turn warm our polar places where the Sun atmosphere (⊳ ), making shines 24 hours a day some regions, such as during the summer ( ⊲). In this spectacular desert other places, on the in Namibia, warmer opposite pole of the planet, than others. there is total darkness during the same 24 hours. What type of energy is in sunlight, and does What causes variations in all of the Sun’s energy the number of daylight hours, make it to Earth’s both from place to place and surface? from season to season? Extratropical regions have seasons, changing from the warm days of summer to the cold, snowy times of winter ( ⊲). Arctic Ocean Greenland Arctic Ocean What causes the change from season to season, and do all areas experience summer at the same time? Asia Asia 02.00.a4 Sapporo, Japan North America Tropical areas like Indonesia ( ⊲) do not have a distinct summer Atlantic and winter but may have a rainy Ocean season and a dry season. Africa Why do some regions experi- Pacific Ocean ence summer and winter but others do not? South Indian America Ocean 02.00.a5 Banda Island, Indonesia Australia Atlantic 02.00.a6 Ocean Antarctica, during its winter, has a dramatic thinning of the overlying ozone layer in the atmosphere, with the area affected shown here in purple (⊳ ). What is ozone, what causes this thinning, and why is there so much global concern about this phenomenon when ozone makes up less than Antarctica 0.001% of all the gas in the atmosphere? Antarctica 34 rey42432_ch02_034-073.indd 34 11/04/16 02:37 PM Final PDF to printer Energy and Matter in the Atmosphere 35 TOPICS IN THIS CHAPTER 2 .1 What Is the Atmosphere? 36 2 .1 2 What Is Ozone and Why Is It So Important? 58 2.2 What Is Energy and How Is It Transmitted? 38 2 .1 3 How Much Insolation Reaches the Surface? 60 2.3 What Are Heat and Temperature? 40 2 .1 4 What Happens to Insolation That Reaches 2.4 What Is Latent Heat? 42 the Surface? 62 2.5 What Is Electromagnetic Radiation? 44 2 .1 5 How Does Earth Maintain an Energy Balance? 64 2.6 What Controls Wavelengths of Radiation? 46 2 .1 6 How Do Insolation and Outgoing Radiation Vary Spatially? 66 2.7 What Causes Changes in Insolation? 48 2 .1 7 Why Do Temperatures Vary Between 2.8 Why Does Insolation Vary from Place to Place? 50 Oceans and Continents? 68 2.9 Why Do We Have Seasons? 52 2 .1 8 CONNECTIONS: How Are Variations in Insolation 2 .1 0 What Controls When and Where the Sun Expressed Between the North and South Poles? 70 Rises and Sets? 54 2 .1 9 INVESTIGATION: How Do We Evaluate Sites 2 .1 1 How Does Insolation Interact for Solar-Energy Generation? 72 with the Atmosphere? 56 02.00.a7 Stonehenge, Wiltshire, England 02.00.a8 West-Central IL Ancient people, such as the builders of Stonehenge ( ⊲) 4,000 years ago, used changes in the position of the Sun over time to schedule important activities, such as the planting of crops. What causes the seasons, and what indicates the end of one season and the start of another? Arctic Ocean Greenland Arctic Ocean Clouds, as in the thunderstorm above (▲), consist of Asia Asia North small drops of water and ice crystals. The water to America make the drops and crystals evaporated from the America surface using energy from the Sun. Atlantic How much energy is needed to cause evaporation, Ocean and where does that energy ultimately go? Pacific Ocean Africa 02.00.a9 Earth and Moon, Lunar Reconnaissance Orbiter South Indian America Ocean Australia Atlantic Ocean A spacecraft orbiting the Moon combined an image it took of Earth with those taken of the lunar surface to 2.0 produce this spectacular portrait (▲) of our planet. Antarctica Antarctica Where does light coming from Earth originate, and 02.00.a1 does this light indicate that Earth is emitting energy? rey42432_ch02_034-073.indd 35 11/04/16 02:37 PM Final PDF to printer 36 2.1 What Is the Atmosphere? A RELATIVELY THIN LAYER OF GAS — the atmosphere — surrounds Earth’s surface. The atmosphere shields us from harmful high-energy rays from space, is the source of our weather and climate, and contains the oxygen, water vapor, and other gases on which all life depends. What is the character and composition of the atmosphere, and how does it interact with light coming from the Sun? What Is the Character of the Atmosphere? 02.01.a1 Arabian Peninsula 02.01.a2 San Luis Valley, CO Examine this view of Earth, taken As viewed from a spacecraft orbiting high from the above the Earth. As viewed from ground, the space, Earth is dominated by three atmosphere things: the blue oceans and seas, mostly the multicolored land, and clouds. appears as a If you look closely at the very blue sky with edge of the planet, you can variable observe a thin blue fringe that is amounts of the atmosphere. From this clouds, which perspective, the atmosphere are commonly appears to be an incredibly thin nearly white layer that envelops our planet, separating us from the dark vastness of space. or some shade of gray. During sunset and sunrise, the sky Clouds, which are so conspicuous in any image of Earth taken from space, mostly can glow reddish or orange. The colors of the sky and circulate within the lower atmosphere, bringing rain and snow. The winds that clouds are due to the way sunlight interacts with matter in move the clouds are also within the lower atmosphere. the atmosphere. What Is the Structure of the Atmosphere? The atmosphere extends from the surface of Earth upward for more than 100 km, with some characteristics of the atmosphere going out to thousands of kilometers. The atmosphere is not homogeneous in any of its attributes, but instead has different layers that vary in temperature, air pressure, and the amount and composition of gases. Each layer has the term “sphere” as part of its name, referring to the way each layer successively wraps around the Earth with a roughly spherical shape. Examine the figure below and then read the text from the bottom left, starting with the lowest and most familiar part of the atmosphere. e 4. The top layer is the thermosphere, derived from the Greek word for heat e 5. On the right side because this layer, surprisingly, can become very hot (more than 1,500°C) as gas of this figure are particles intercept the Sun’s energy. It is the altitude where the spectacular auroras scattered bright dots (i.e., “Northern Lights”) originate from interactions of solar energy and energetic that represent gas hermospher hermospher T gas molecules. T molecules in the atmosphere. The 3. Above the stratosphere is the mesosphere, where “meso” is Greek for “middle,” 80km ˜90°C molecules are as this layer is in the middle of the atmosphere. The mesosphere starts at 50 km, infinitely smaller and e the top of the stratosphere, and goes up to more than 80 km (~50 miles) in e more abundant than altitude. The upper part of the mesosphere is very cold (−85°C, −120°F), and is shown here. Note considered by many scientists to be the coldest place within the Earth system. It is that the molecules within the mesosphere that most small meteors burn up, producing the effect are concentrated Mesospher Mesospher called “shooting stars.” Radio waves from Earth bounce off this layer and the TEMPERATURE lower in the atmo- overlying layer, allowing us to hear radio stations from far away. sphere and become 50km 0°C 2. The next layer up is the stratosphere, beginning at an altitude of about 10 km much more sparse above sea level, at about the elevation of Earth’s highest peaks. The name is upward. Over derived from a Latin term for spreading out, referring to its layered (not mixed) 70% of the mass of character. Temperatures are also stratified, varying from cooler lower altitudes to the atmosphere is warmer upper ones. The lowest part of the stratosphere is an altitude at which in the lowest 10 km, many commercial jets fly because the air offers less resistance to motion, allowing that is, within the ratosphere appreciable fuel savings. ratosphere troposphere. The St St mesosphere and 1. The lowest layer is the one with which we surface-dwellers interact. It contains thermosphere the air we breathe, clouds, wind, rain, and other aspects of weather. This layer is contain only a few 10km ˜7 0°C - e - the troposphere, with the name “tropo” being derived from a Greek word for e tenths of a percent turning or mixing, in reference to the swirling motion of clouds, wind, and other of the atmosphere’s ropo ropo T spher manifestations of weather. T spher mass. 02.01.b1 rey42432_ch02_034-073.indd 36 11/04/16 02:37 PM Final PDF to printer Energy and Matter in the Atmosphere 37 What Is the Composition of the Atmosphere? The atmosphere is not completely homogeneous in its vertical, horizontal, or temporal composition, but chemists and atmospheric scientists have estimated its average composition, as represented in the graph and table below.