The Earth and Its Atmosphere Chapter 1 The Earth and Its Atmosphere

Overview of the Earth’s Atmosphere The atmosphere is a delicate life-giving blanket of air surrounding the Earth. Without the atmosphere the Earth would not have lakes or oceans. Radiant energy from the sun energizes the atmosphere driving day to day weather.

Figure 1. 1: The earth’s atmosphere as viewed from space Figure 1.1: The earth’s atmosphere as viewed from space. The atmosphere is the thin blue region along the edge of the earth. Fig. 1-1, p. 5

Overview of the Earth’s Atmosphere Composition 99% of the atmosphere is within 30km of the Earth’s surface. N2 78% and O2 21% The percentages represent a constant amount of gas but cycles of destruction and production are constantly maintaining this amount.

Table 1-1, p. 5

Overview of the Earth’s Atmosphere Composition Water is a variable gas following the hydrologic cycle. Carbon dioxide has risen in recent years and is an important greenhouse gas. Other greenhouse gases exist beyond carbon dioxide. Ozone – surface, upper, hole Aerosols

Figure 1.3: The main components of the atmospheric carbon dioxide cycle. The gray lines show processes that put carbon dioxide into the atmosphere, whereas the red lines show processes that remove carbon dioxide from the atmosphere. Fig. 1-3, p. 7

FIGURE 1.3 The main components of the atmospheric carbon dioxide cycle. The gray lines show processes that put carbon dioxide into the atmosphere, whereas the red lines show processes that remove carbon dioxide from the atmosphere. Figure 1.3: The main components of the atmospheric carbon dioxide cycle. The gray lines show processes that put carbon dioxide into the atmosphere, whereas the red lines show processes that remove carbon dioxide from the atmosphere. Stepped Art Fig. 1-3, p. 7

Figure 1.4: Measurements of CO2 in parts per million (ppm) at Mauna Loa Observatory, Hawaii. Higher readings occur in winter when plants die and release CO2 to the atmosphere. Lower readings occur in summer when more abundant vegetation absorbs CO2 from the atmosphere. The solid line is the average yearly value. The concentration of CO2 has increased by more than 20 percent since 1958. (Data from NOAA) Fig. 1-4, p. 7

Figure 1.5: The darkest color represents the area of lowest ozone concentration, or ozone hole, over the Southern Hemisphere on September 22, 2004. Notice that the hole is larger than the continent of Antarctica. A Dobson Unit (DU) is the physical thickness of the ozone layer if it were brought to the earth’s surface, where 500 DU equals 5 millimeters. Fig. 1-5, p. 8

Figure 1.6: Erupting volcanoes can send tons of particles into the atmosphere, along with vast amounts of water vapor, carbon dioxide, and sulfur dioxide. Fig. 1-6, p. 8

Overview of the Earth’s Atmosphere The Early Atmosphere The Earth’s first atmosphere was composed mostly of hydrogen and helium (most abundant gases in the universe). The atmosphere evolved due to outgassing of CO2 and H2O from the cooling center of the Earth causing rain and eventually lakes and oceans. Lakes and oceans acted as a sink, absorbing CO2 from atmosphere. Plants evolved producing oxygen to form our current atmosphere several 100 million ybp. First atmosphere probably escaped to outer space. Second atmosphere: Volcano gas emissions: 80% water vapor, CO2 10% Oxygen probably came from split water vapor where H escaped to outer space, but O remained in the atmosphere.

Overview of the Earth’s Atmosphere This video shows someone’s overview of the change in composition of earth’s atmosphere through time. The presenter shows what changed and lists reasons why it changed. Is it successful? Is it fun? First atmosphere probably escaped to outer space. Second atmosphere: Volcano gas emissions: 80% water vapor, CO2 10% Oxygen probably came from split water vapor where H escaped to outer space, but O remained in the atmosphere. http://www.youtube.com/watch?v=UpvsUwxJgYY&feature=player_detailpage

Vertical Structure of the Atmosphere Air Pressure and Air Density Weight = mass x gravity Density = mass/volume Pressure = force/area At the Earth’s surface the pressure of the atmosphere is 14.7 lbs/in2 . Standard sea level pressure is 1013.25 mb = 1013.25 hPa = 29.92 in Hg Atmospheric pressure decreases with an increase in height. Weight of all air in atmosphere ~= 5,600 trillion tons hPa = hectopascals In Hg = inches of mercury

Figure 1.7: Both air pressure and air density decrease with increasing altitude. The weight of all the air molecules above the earth’s surface produces an average pressure near 14.7 lb/in2. Fig. 1-7, p. 10

Figure 1. 8: Atmospheric pressure decreases rapidly with height Figure 1.8: Atmospheric pressure decreases rapidly with height. Climbing to an altitude of only 5.5 km, where the pressure is 500 mb, would put you above one-half of the atmosphere’s molecules. Fig. 1-8, p. 10

Vertical Structure of the Atmosphere This video describes why it is colder on top of mountains and warmer closer to sea level. Is it successful? Is it fun? http://www.youtube.com/watch?v=gGNxYtT_36I&list=FLA8rzatZrvuFZS5jkp0XvIg&index=3&feature=plpp_video Weight of all air in atmosphere ~= 5,600 trillion tons hPa = hectopascals In Hg = inches of mercury

Class Exercise 1 Complete Table 1-1 and then plot the data on the graph. Here is the “rule of thumb” you can use to complete the table: “For every 5.6 km you ascend, there is half the atmospheric mass above you as when you started.”

Class Exercise 1 X X X X

Vertical Structure of the Atmosphere Observation: Radiosonde Weather balloon Instrument and transmitter Air temperature, humidity, pressure

Vertical Structure of the Atmosphere Layers of the Atmosphere Lapse rate = change in temperature with a change in height Isothermal environment = no change in temperature with height Inversion layer = change in the sign of the lapse rate

Vertical Structure of the Atmosphere Layers of the Atmosphere http://www.youtube.com/watch?v=nOvcz3nHuzo&list=UU7SQV7C-GSJfLDRIJmutuDQ&index=63&feature=plpp_video Troposphere: decrease in temperature, day to day weather, tropopause Stratosphere: increase in temperature, ozone, stratopause Mesosphere: decrease in temperature, mesopause Thermosphere: increase in temperature, suns strongest radiation

Figure 1.9: Layers of the atmosphere as related to the average profile of air temperature above the earth’s surface. The heavy line illustrates how the average temperature varies in each layer. Fig. 1-9, p. 11

Figure 1.9: Layers of the atmosphere as related to the average profile of air temperature above the earth’s surface. The heavy line illustrates how the average temperature varies in each layer. Stepped Art Fig. 1-9, p. 11

Class Exercise 2 Complete Table 1-2 and then plot the data on the graph. Here is the “rule of thumb” you can use to complete the table: “When averaged over all seasons, air temperature is 15 deg C at the earth’s surface and decreases by 6.5 deg C per kilometer in the lowest 11 km. Consequently, this decrease is often referred to as the average lapse rate – the average for all locations and seasons”

Class Exercise 2

Figure 1.10: Layers of the atmosphere based on temperature (red line), composition (green line), and electrical properties (blue line). (An active sun is associated with large numbers of solar eruptions.) Fig. 1-10, p. 13

Vertical Structure of the Atmosphere The Ionosphere Not a true layer but an electrified region Ions = molecule with an additional or minus an electron Exists at the top of the atmosphere in the thermosphere F,E,D layer Sun light creates layers, D disappears at night and less interference with AM radio transmissions

Figure 1.11: At night, the higher region of the ionosphere (F region) strongly reflects AM radio waves, allowing them to be sent over great distances. During the day, the lower D region strongly absorbs and weakens AM radio waves, preventing them from being picked up by distant receivers. Fig. 1-11, p. 14

BREAK TIME!, then…. Weather and Climate Weather: short term air temperature, air pressure, humidity, clouds, precipitation, visibility, and wind Climate: long term patterns and average weather; not just magnitude but also frequency

Weather and Climate Satellite’s View Geostationary satellite Meridians measure longitude (W-E) Parallels measure latitude (N-S) Weather maps: pressure cells, fronts, surface stations

Figure 1.16: Ice storm near Oswego, New York, caused utility poles and power lines to be weighed down, forcing road closure. Fig. 1-16, p. 21

Weather and Climate Storms of All Sizes Middle-latitude cyclone Hurricane Thunderstorms Tornadoes

Weather and Climate A Look at the Weather Map Wind Wind direction Wind speed Front

Figure 1.12: This satellite image (taken in visible reflected light) shows a variety of cloud patterns and storms in the earth’s atmosphere. Fig. 1-12, p. 16

“Fronts” A cold front is defined as the leading edge of a cooler mass of air, replacing (at ground level) a warmer mass of air, which lies within a fairly sharp surface trough of low pressure. Figure 1.12: This satellite image (taken in visible reflected light) shows a variety of cloud patterns and storms in the earth’s atmosphere.

Figure 1.13: Simplified surface weather map that correlates with the satellite image shown in Fig. 1.12. The shaded green area represents precipitation. The numbers on the map represent air temperatures in °F. Fig. 1-13, p. 17

Figure 1.15: Doppler radar has the capacity of estimating rainfall intensity. In this composite image, the areas shaded green and blue indicate where light-to-moderate rain is falling. Yellow indicates heavier rainfall. The red-shaded area represents the heaviest rainfall and the possibility of intense thunderstorms. Notice that a thunderstorm is approaching Chicago from the west. Fig. 1-15, p. 20

Figure 2: Doppler radar image showing the heavy rain and hail of a severe thunderstorm (dark red area) over Indianapolis, Indiana, on April 14, 2006. Fig. 2, p. 18

Weather and Climate Meteorology Study of the atmosphere and its phenomena Aristotle 340 B.C. Meterologica, meteoros: high in air 1843 telegraph 1920s air masses 1940s upper air 1950s radar and computers 1960s satellite

Weather and Climate Weather and Climate in Our Lives Two general reasons for studying how weather and climate impacts our lives: economic efficiency and public safety. Clothing Crops Utilities Extreme cold and heat Tornados and hurricanes

Figure 1.17: A tornado and a rainbow form over south-central Kansas during June, 2004. Fig. 1-17, p. 21

Figure 1.18: Extensive damage caused by a violent tornado that moved through Parkersburg, Iowa, on May 5, 2008. Fig. 1-18, p. 21

Figure 1.19: Flooding during May, 2010, inundated Nashville, Tennessee. Flood waters of the Cumberland River extend over much of the town, including the Grand Ole Opry. Fig. 1-19, p. 22

Figure 1.20: Estimates are that lightning strikes the earth about 100 times every second. About 25 million lightning strikes hit the United States each year. Here, lightning strikes the ground and illuminates the sky over Tucson, Arizona. Fig. 1-20, p. 22

Figure 3: A model that simulates a three-dimensional view of the atmosphere. This computer model predicts how winds and clouds over the United States will change with time. Fig. 3, p. 23

Weather and Climate Career: Meteorologist Any person with a college degree in meteorology or atmospheric science; not just the TV weather person Half of 9000 meteorologists employed by the US National Weather Service Researchers and operational meteorologists What is happening today in the southeastern United States? http://weather.gov