Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Atmosphere and Climate Julieanne Quigley 2.2017 The Atmosphere • The nearby planets of Mars and Venus are barren and lifeless. Why does our planet have life? • One thing that makes life possible on earth is its atmosphere • The atmosphere is a thin layer of gases that surround the earth The Atmosphere • The atmosphere is 78% nitrogen and 21 % oxygen. The remaining 1% is: water vapor, argon, carbon dioxide, neon, helium and other gases. • We call this entire mixture air. • The most important of the air’s gases for organisms are oxygen and carbon dioxide The Atmosphere • Oxygen is necessary for cellular respiration and carbon dioxide is necessary for photosynthesis • The earth’s atmosphere protects living things from most of the sun’s harmful UV radiation at the same time it allows visible light to reach the earth’s surface supplying earth with energy and making photosynthesis possible Photosynthesis and the Atmosphere • Living things played a very important role in forming the atmosphere we know today. • Early earth’s atmosphere contained very little oxygen and a lot of CO2 • Early organisms evolved the ability to do photosynthesis and slowly changed the atmosphere from high levels of CO2 to high levels of oxygen Layers of the Atmosphere • Scientists have found it useful to think of the atmosphere as five individual layers. – – – – – Troposphere Stratosphere Mesosphere Thermosphere Exosphere Layers of the Atmosphere • The troposphere extends from the earth’s surface to about 10km above the surface • It contains about 90% of the atmosphere’s gases • The air we breathe is a part of the troposphere • It is where weather occurs Layers of the Atmosphere • The Stratosphere extends from 10kn -50km above the earth. • The air in the stratosphere is less dense • Commercial airliners often travel in the lower part of the stratosphere • Stratosphere contains the ozone layer Layers of the Atmosphere • Beyond the stratosphere is the mesosphere, thermosphere and the exosphere • The gases in the exosphere become thinner and thinner until the exosphere merges with outer space Climate • Weather occurs mostly in the troposphere, the atmospheric layer that touches the earth’s surface, but… • WHAT IS WEATHER?? Climate • Weather is simply what is happening in the atmosphere at a particular place at a particular moment • Climate on the hand, is the average weather in an area over a long period of time • Temperature, humidity, wind and precipitation are important factors in determining climate Climate • Climate is determined by a variety of factors: latitude, air circulation, ocean currents and local geography of the area. • The most important of these factors is latitude Latitude • Latitude is the distance from the equator, measured in degrees north or south of the equator • The equator is defined as 0⁰. • The most northerly latitude is the North Pole, at 90⁰ North • The most southerly latitude is the South Pole, at 90⁰ South Latitude • Latitude strongly influences climate because the amount of solar energy an area receives depends on latitude • More solar energy falls on areas near the equator that areas closer to the poles Atmospheric Circulation Patterns • Three important properties of air explain how air circulation affects climate: – Cold air sinks and warms as it sinks – Warm air rises and cools as it rises – Warm air can hold more water vapor than cold air can therefore, if warm air is cooled, the water vapor it contains condenses into a liquid forming rain or snow Atmospheric Circulation Patterns • Solar energy heats the ground, which warms the air above it. This warm air rises, and cooler air moves in to replace it. Heating of the atmosphere therefore causes wind, or the movement of air within the atmosphere • Because different latitudes receive different amount of solar energy, the patterns of global circulation result Atmospheric Circulation Patterns • The circulation pattern determines global patterns of precipitation • Rainforest example: Intense solar energy strikes the earth’s surface at the equator causing the air above it to become warm, this warm air can hold large amounts of water that evaporates from the ocean and land. As the air rises, however, it cools and loses some of its ability to hold water, thus, it rains heavily at the equator! Atmospheric Circulation Patterns • Desert example: cool air normally sinks, but the cool air over the equator cannot descend because hot air is moving up below it. So this cool air is forced away from the equator, toward the poles. It sinks back to earth at a latitude of about 30⁰, warming as it falls. This warm, dry air moves across the surface causing water to evaporate from the land below causing extremely dry conditions! Ocean Circulation Patterns • Ocean currents have a great effect on climate because water hold large amounts of heat. • The movement of surface ocean currents is caused largely by winds and the rotation of the earth. • These currents redistribute warm and cool masses of water Seasons • Temperature and precipitation change with the seasons. • Seasons are the result of the earth’s orbit around the sun, earth has a 23⁰ tilt which means the angle at which the sun’s rays strike the earth changes as the earth moves around the sun. • During spring and summer the northern hemisphere tilt toward the sun and the southern hemisphere tilts away. It is the opposite in the fall and winter Seasons • Four seasons do not occur in the tropics, which are the so close to the equator, they receive direct sunlight year round. • In the far north and far south there are months of complete darkness and complete light Greenhouse Earth • Have you ever gotten in your car that has been sitting the sun for a while with all the windows closed. Even if the day is cool, the air inside the car is much warmer than the air outside. • Heat builds up inside the car because the sun’s energy streams into the car through the glass, carpets and upholstery absorb the heat and the heat energy doesn’t pass back out though the glass The Greenhouse Effect • The earth is similar to a green house. We live inside “greenhouse earth” like delicate plants, surrounded by the icy coldness of outer space. • The earth’s atmosphere acts like the glass in a green house, sunlight streams through the atmosphere and heats the earth. The Greenhouse Effect • As heat radiates up from the earth, some of it escapes into space. • The rest of the heat is trapped by gases in the troposphere and warms the air • This process is called the greenhouse effect The Greenhouse Effect • Not every gas in our atmosphere traps heat. The gases that DO trap and radiate heat are called greenhouse gases • The major greenhouse gases are water vapor, carbon dioxide, chlorofluorocarbons (CFCs), methane, and nitrous oxide. • After water vapor, carbon dioxide is the most important of the greenhouse gases. Carbon Dioxide • Carbon dioxide levels are rising globally. • Carbon dioxide levels rise and fall with the daily rhythms of photosynthesis, but due to fossil fuel burning and industrial pollution the carbon dioxide levels have been increasing over the past 50 years at an alarming rate. Carbon Dioxide • During photosynthesis, a plant takes in carbon dioxide from the air, some of the carbon in the carbon dioxide becomes part of the plant’s body, this carbon is not returned o the air • When fossil fuels are burned, carbon is released into the air. • If the amount of carbon dioxide is low, plants are able to recycle it… but, there is too much carbon for plants to recycle all of it Carbon Dioxide and Greenhouse Gases • Since greenhouses gases trap heat hear the earth’s surface, many scientists think that more greenhouse gases in the atmosphere will result in a warmer earth • Today we are releasing more carbon dioxide into the atmosphere than any other green house gas along with many others • Global warming is a predicted increase in temperature due to too many greenhouse gases Warmer Earth… • The earth’s climate has changed dramatically in the past as over hundreds and thousands of years • Currently scientists believe the earth’s climate is changing very rapidly due to increases in carbon Warmer Earth • Weather patters- change as climate changes. Hurricanes and typhoons are more common, severe flooding and devastating droughts • Agriculture- disruptions in earth patterns hit farmers very hard. As temperatures change, farming becomes more and more difficult • Sea levels- as polar regions warm, icebergs break loose from glaciers and let in the sea causing sea levels to rise and coastal cities to be in danger of flooding Slowing the temperature change • Reduce fossil fuel use • Reduce carbon footprint • Forests should be preserved • More trees should be planted • Monitor greenhouse gas emissions • Create laws banning greenhouse gases The Ozone Shield • The stratosphere contains the earth’s ozone shield • Ozone is a form of oxygen with molecules made of three oxygen atoms • Ozone in the stratosphere absorbs most of the UV light from the sun • UV light is very harmful to organisms because it can damaged DNA in living cells • Shielding the earth’s surface from most of the sun’s UV radiation, the ozone in the stratosphere acts like sunscreen for the earth Ozone Eaters • During the 1970’s scientists discovered chlorofluorocarbons were damaging the ozone. CFC’s were used in coolants and spray bottles • CFC’s are stable at the earth’s surface, but as they move up in the atmosphere, they break the bonds of the ozone. It is thought that a single CFC can break apart as many as 10,000 ozone molecules The Ozone Holes • NASA stated: Ozone layers near the south pole had thinned by up to 90% in the early 1990’s. • After this was discovered, laws were put into place to limit greenhouse gases and to try to protect the ozone Thinning Effects • As the ozone decreased, more UV light was able to enter the earth. UV light is dangerous because it can alter DNA in organisms. • High levels of UV light can destroy single celled organisms and cause mutations in larger organisms. • Skin cancer has increased dramatically in humans over the last 20 years. Ozone Healing… • Since the 1990’s – Industrialized countries agreed to eliminate more CFC’s by 1995 – The US banned all substances that pose a danger to the ozone by 2000 – Industrialized countries agreed to set up a fund to help developing countries switch to substitutes for CFC’s • More recently- A huge “Green” movement is sweeping the world and most people are working hard to recycle, reduce carbon foot print, reduce fossil fuels and do as much as they can to protect the ozone and the entire planet