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ENV CHAPTER 13-1: CLIMATE AND CLIMATE CHANGE
Weather = the state of the atmosphere at a particular place and timeClimate = long-term prevailing weather conditions at a certain place based on records taken Factors that determine climate:1. Latitude (the most important factor) – distance from the equatora. Equator is at 0, north pole is at 90N, south pole is at 90Sb. It influences the amount of solar energy an area receives i. Low latitudes – sun’s rays strike straight on; more solar energy falls there, night and day are 12 hrs, high temps, no summers or winters ii. High latitudes – sun’s rays strike at an angle so the energy is spread out; less solar energy, amount of daylight varies, temperature variesc. Because different amounts of solar energy fall on different parts of the earth, different parts of the earth have different climates. d. The seasons are caused by the tilt of the earth on its axis as the earth revolves around the sune. There are no seasons at the equator because solar rays strike earth at almost a 90 degree angle year round. 2. Atmospheric circulation patternsa. Cold air sinks b/c it is denser than warm air i. As cold air sinks it compresses and warmsb. Warm air rises – it expands and cools as it rises i. Warm air can hold more water vapor than cold airii. When warm air cools the water vapor it has may condense into liquid to form rain, snow, or fogc. wind – movement of air within the atmosphere i. global circulation patterns are created by mass movements of airii. prevailing winds = winds that blow predominantly in one direction throughout the year.-Tradewinds = between 30 N and S-Westerlies = between 30 and 60 3. Oceanic circulation patternsa. Affect climate b/c water holds a lot of heatb. Ocean currents are caused mostly by wind and the rotation of earthc. El nino (Southern Oscillation) – short-term change in the location of warm and cold water masses in the Pacific i. Winds strengthen and push warm water east. Rains follow. ii. El nino is the warm phase, la nina is the cool phase.d. Pacific decadal oscillation – long-term change (20-30 yr) in the location of water masses in the pacific 4. Geography/topography – height above sea levela. Temperatures fall 6 degrees per 1000 meter increase in elevationb. Mountains and mountain ranges influence the distribution of precipitation – rain shadow 5. Solar activity – increased solar radiation, more ozone, warms6. Volcanic activity – sulfur dioxide haze from eruptions reflects sunlight to cause global temperatures to decrease
ENV CHAPTER 13-2: THE OZONE SHIELD
Ozone layer = area in the stratosphere where ozone (O3) is highly concentrated- it absorbs most of the UV light from the sun (like global sunscreen) chlorofluorocarbons (CFCs) = class of human-made chemicals that damage the ozone layer- nonpoisonous, nonflammable, coolants, fizz in foams, propellant in sprays- stable at earth’s surface but unstable in the stratosphere- UV light breaks down CFCs > it releases a Cl atom > the Cl reacts with O3 to create chlorine monoxide (ClO) and O2 > the ClO reacts with O3 (stealing the ozone molecules) creating O2 and Cl. Hole in the ozone = thinning of stratospheric ozone that occurs over the poles in the springHow it forms:- During the dark polar winter, polar vortex winds suck in cold air and temperatures fall below –80. This results in high-altitude clouds made of water and nitric acid called polar stratospheric clouds.- Products of CFCs are converted to molecular Cl2 on the surface of these clouds.- During the polar spring, sunlight splits the Cl2 into 2Cls which break apart O3. Effects of ozone thinning – we’re all exposed to more UV which damages DNA1. humans – skin cancer, cataracts, weakened immune response2. animals – genetic mutations, death of phytoplankton and the disruption of food chains, reduction in amphibians (hurts their eggs)3. plants – interference with photosynthesis, reduced crop yields Protecting the ozone layer- Limit the production and use of CFCs, use CFC replacements- Success in getting the global community to cooperate- The hole is going to be there for a while though – CFCs can be active for 60-120 years, so molecules released years ago will be damaging the ozone for years to come.ENV CHAPTER 13-3: GLOBAL WARMING
The greenhouse effect = where earth’s atmosphere acts like the glass in a greenhouseGreenhouse gases = gases that absorb and radiate heat.- Water vapor- Carbon dioxide (does most of it)- CFCs- Methane- Nitrous oxide How it happens: 1. solar radiation warms the earth’s surface 2. it’s absorbed and radiated into the atmosphere as heat 3. greenhouse gases absorb the heat and radiate it back toward the earth’s surface. [A greenhouse lets in solar radiation to heat the air, and the glass prevents the warm air from escaping.] The average yearly concentration of carbon dioxide in the atmosphere has been increasing- Increases by a few parts per million each year- Measurements started by Keeling on the top of volcano Mauna Loa in Hawaii- Burning fossil fuels, vehicles, industry add to the CO2 Scientists have confirmed that b/c greenhouse gases trap heat near the earth’s surface, more greenhouse gases in the atmosphere will result in an increase in global temperature.- comparison of CO2 in the atmosphere and average global temperatures support this view. Global warming = an increase in global temperature- due to the increase in greenhouse gases in the atmosphere - increase in greenhouse gases are due to human activity (burning fossil fuels, industrialization, deforestation, etc.)Consequences of a warmer earth1. Melting ice and rising sea levels – coastal regions affected, flooding, erosion2. Global weather patterns – surface ocean currents could change and thus affect weather patterns3. Human health problems – heat-related deaths, increased surface O3 so increased respiratory problems, increased insect-borne disease.4. Agriculture – drought, decreased crop yields5. Plants and animals – change in ranges of species and communities (land and aquatic) Findings – from the Intergovernmental Panel on Climate Change (IPCC)Temperature rising, human activities are putting more greenhouse gases into the atmosphere, sea levels are rising, etc. Reducing the risk:- Kyoto Protocol – requires developed countries to decrease emissions of CO2 and other greenhouse gases- Reforestation projects- Paris Agreement - developed countries commit to keeping warming below 2 degrees
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