You awake one winter morning to snow falling. When you look out your window at noon, the snow had changed to rain, and later in the afternoon sleet was falling. This later turned to snow. As you are driving home from work, evening rain was freezing on bri

ES 1010, Earth Science 1 Cou rse Learning Outcomes for Unit VI Upon completion of this unit, students should be able to: 8. Relate how radiation and atmospheric processes control weather and climate. 8.1 Discuss how the atmosphere affects weather and climate. 8.2 Explain the possible pathways of incoming solar radiation and how this is affected by elevation, latitude, and the angle of the Earth’s tilt. 8.3 Explain the role of temperature and water vapor as it relates to weather. Reading Assignment Chapter 11: Heating the Atmosphere Chapter 12: Moisture, Clouds, and Precipitation Environmental Protection Agency. (2010). Ozone science: The facts behind the phaseout. Retrieved from http://www.epa.gov/ozone/science/sc_fact.html National Oceanic and Atmospheric Administration. (2015). Global warming. Retrieved from http://www.ncdc.noaa.gov/monitoring -references/faq/global -warming.php National Aeronautics and Space Admi nistration. (2015). Temperature puzzle [Video file]. Retrieved from http://climate.nasa.gov/climate_resources/42/ Williams, C. [IDT -CSU]. (2015, August 7). Local winds final [Video file]. Retrieved from https://youtu.be/MjkJfPjBZEA In order to access t he resource below, you must first log into the MyCSU Student Portal and access the General OneFile database within the CSU Online Library. Peck, S. W., & Richie, J. (2009). Green roofs and the urban heat island effect: Roofing materials can absorb energy from the sun and convert it to sensible heat, contributing to the urban heat island effect. Buildings , 103 (7), 1 -5. UNIT VI STUDY GUIDE Earth’s Atmo sphere ES 1010, Earth Science 2 UNIT x STUDY GUIDE Title Unit Lesson W eather affects our day -to-day lives and activities. Depending on the season and climate of our region, we could expect sun, rain, snow, wind, or thunderstorms on any given day. For most of us, checking the local weather forecast is one of the first things we do each day. It is important to distinguish between weather and climate. W eather is constantly changing; in some regions it may seem like the weather changes on an hourly basis! The long -term average weather of a region defines its climate. This unit wi ll focus on both weather and climate and how it is regulated by the atmosphere and location. First, is important to understand the make -up of our atmosphere, which affects the amount of solar radiation absorbed and reflected back to space. Our atmosphere is mainly composed of nitrogen (N 2) and oxygen (O 2), with other gases present in trace amounts. The atmosphere is divided into several layers: the troposphere, stratosphere, mesosphere, and thermosphere. The troposphere is the lower -most layer and the layer that affects our weather the greatest. In this layer, temperature and air pressure decrease with altitude.

Because of these factors, this layer produces clouds and precipitation. The next layer, the stratosphere, is where the ozone layer is found — cau sing temperatures to be fairly constant and slightly warmer. The ozone is the layer that absorbs harmful UV radiation and makes life on Earth possible. The mesosphere is the coldest layer, with decreasing temperatures as the altitude increases. In the four th layer, there is no upper limit. It basically extends into space. Temperatures are very high due to intense solar radiation (Lutgens & Tarbuck, 2014). It is also important to understand the relationship of the Sun and the Earth. Weather is driven by so lar radiation. The amount of solar radiation from place to place is dependent on the angle of the Sun’s rays.

When solar radiation is perpendicular to the surface of the Earth, more energy is absorbed. At lower angles, the Earth’s atmosphere will cause mor e reflection of this energy, resulting in lower temperatures. Because the Earth’s axis is tilted, the direction of the Sun’s rays varies at any given point as the Earth rotates around it.

When the Northern Hemisphere is tilted towards the Sun, we experienc e summer. W hen it is tilted away from the Sun, we experience winter. This also affects the day length at any given point on Earth. During summer, the pole that is tilted towards the sun will have much longer days (more hours of sunlight). In fact, on the summer solstice, the pole tilted towards the Sun will have 24 hours of daylight and the pole tilting away from the Sun will have 24 hours of darkness. These differences are diagramed in Figure 11.16 (p. 365 ). Notice that the day length at the equator nev er changes (12 hours of light). Because of this, areas around the equator do not experience changing seasons. So, what happens when the Sun’s radiation strikes the Earth? The Sun’s radiation (short -wave radiation) can either be absorbed by land, sea, and clouds, or reflected back to space. Figure 11.20 (p. 370) shows these different pathways. The amount of radi ation reflected largely depends on something called albedo . Albedo is the reflectivity of a surface. Light -colored surfaces have will have a high albedo and reflect much of the sun’s energy back to space. Dark -colored surfaces will have a lower albedo, abs orbing more heat energy. Much of the radiation absorbed by the earth and sea will be re -radiated back towards the atmosphere (long -wave radiation). The gases in the atmosphere can trap a lot of this long -wave radiation, which is essential to keep the Earth ’s temperature warm enough for life. We refer to this phenomenon as the greenhouse effect . The main greenhouse gases , carbon dioxide and water vapor, allow short -wave radiation to pass through, but block long -wave radiation from leaving the atmosphere. In recent decades, it has been noted that the Earth’s average temperature has been steadily increasing. This correlates to the increasing levels of carbon dioxide in the atmosphere. This video from NASA (2011) summarizes this phenomenon and the potential effects of global warming. As you can see, there are so many interacting forces that affect the Earth’s climate, it is hard to predict exactly how global warming might affect us. Cumulonimbus cloud seen from 38,000 feet (NOAA, 2015). ES 1010, Earth Science 3 UNIT x STUDY GUIDE Title What are some o f the factors that affect regional temperature variations? Latitude, which determines the amount of solar radiation at a given place, is the main cause for temperature differences from place to place (see Table 11.3, p. 356 ). The distance from the coast will also affect regional temperatures. Because water has a higher specific heat (it requires more energy to change the temperature of water), it will maintain its temperature much longer than adjacent land. This has a moderating effect on coastal climate s. If you compare a coastal city to an inland city at the same latitude, you will find that the temperature fluctuates much less near the coast (see Figure 11.32). As we learned in Unit V, the ocean currents can have a significant impact on coastal climate s, bringing in warm or cool waters (depending on the coast). This video from NASA (2012) summarizes how the oceans affect weather and climate. Altitude, as discussed above, will also cause temperature to chan ge. The higher the elevation, the cooler the temperature will be. Local weather conditions may also be impacted by cloud cover and albedo. Temperature is the main driver of weather and climate. The second is water vapor. The amount of water vapor in the a ir is referred to as humidity. As temperatures increase, air is able to hold more water vapor. We measure the actual amount of water vapor in the air and compare that to the potential amount of water vapor that the air could hold at saturation (varies with temperature). This is referred to as relative humidity . Therefore, on a hot summer day it may be much more humid than on a colder day, yet the relative humidity will be lower. As temperatures decrease, the air will become saturated and the water vapor con denses to form a liquid. This will form either fog or clouds. W hen moist air cools near the ground level, fog will form. For clouds and precipitation to form, moist air must be lifted to what is referred to as the condensation point . This is the point wh ere the temperature decreases enough that the air becomes saturated and the water vapor becomes a liquid. Why does air cool as it rises? As described earlier, air pressure decreases with altitude. As air pressure decreases, the air molecules spread further apart and there is less heat energy as molecules collide less often. This phenomenon is known as adiabatic temperature change : as air rises, it expands and cools; as it descends, it condenses and warms. However, it is important to note that air will gener ally not rise on its own. There has to be some mechanisms that forces air upwards in order for clouds to form. These mechanisms include convective lift (air warms from the land below and rises as it becomes less dense), frontal wedging (the collision of wa rm and cool air fronts), convergence (the interaction of as air masses as they come together), and orographic lift (Lutgens & Tarbuck, 2014). Orographic lift is actually a geographic phenomenon that is responsible for a lot of the deserts in the world.

This occurs as warm, moist air (usually from the ocean) is forced over a mountain range. As the air ascends, it cools and drops its moisture in the form of precipitation. As it crosses over the mountain range, it then descends and warms. Therefore, the wind ward side of the mountains is often green and lush, while the leeward side is arid and quite barren. The Great Basin of the U.S. (Nevada, Utah, and Idaho) is a good example of the leeward side of the Sierra Nevada Range. It is the interaction of temperatu re and water vapor that will determine what kind of weather an area receives. This is often seasonal and depends on many atmospheric factors. Consider your local region. What type of climate do you experience? What do you think the driving factors are that determine the weather of your region? In Unit VII, we will go into more depth on the factors that drive local weather conditions. References Lutgens, F. K., & Tarbuck, E. J. (2014). Foundations of Earth Science (7th ed.). Upper Saddle River, NJ: Pearson. National Aeronautics and Spa ce Administration. (2011). Global warming. Retrieved from http://climate.nasa.gov/warmingworld/ National Aeronautics and Space Administration. (2012). The ocean — a driving force for weather and climate. Retrieved from http://svs.gsfc.nasa.gov/cgi -bin/details.cgi?aid=11056 National Oceanic and Atmospheric Administration. (2015). Cumulonimbus cloud seen from 38,000 feet [Image]. Retrieved from http://www.srh.noaa.gov/jetstream/clouds/images/cloud1.jpg ES 1010, Earth Science 4 UNIT x STUDY GUIDE Title Suggested Reading The links below will direct you to both a PowerPoint and PDF view of the Chapter 11 and 12 Presentations.

This will summarize and reinforce the information from these chapters in your textbook. Click here to access the Chapter 11 PowerPoint Presentation. (Click here to access a PDF version of the presentation.) Click here to access the Chapter 12 PowerPoint Presentation. (Click here to access a PDF version of the presentation.)