ATM 103 FINAL EXAM NOTES PDF

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Prof. Kevin Reed...

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11.7.19 -Sun is main driver of climate, weather Impacts of Drought • Droughts often come with a huge price tag and it can have a ripple effect through the economy o Drought in Cali, impacts grocery store prices all across America § When you have shortages in places that produce crops, the price increases • ~$5 billion per year in US • Hard to quantify death related to drought o Accounts for about 20% (from heat waves and drought) of all deaths due to weather § Higher percentage because we are not as good at predicting them as compared to hurricane/tropical storm/cyclone/etc. § MOST DEADLY EXTREME WEATHER EVENT : DROUGHT o More deadly than events like flooding and lightning • CASE STUDY: California Drought o 2011-2014 was the driest period in California record-keeping history o In 2013, rainfall was less than 34% of the normal § Got 1/3 of the rain they usually would get • This is the persistence aspect because it got worse and worse o This includes significant decreases in snowfall and mountain snowpack o Reservoirs are an important aspect to look at because snowpack melts and gets stuck in the Reservoirs which is where people get their water from § Water quality decreases because it has been sitting there for years § Small amount of water leads to lower quality water o IMPACTS: § Streams and rivers are low, and fish can’t get to spawning grounds to lay their eggs and hatch, threatening many species § California has tightened fishing restrictions § Mandatory water restrictions have been put into place by governor of California • THROUGHOUT WHOLE STATE • Restricted who can use water and when they can use it § ~12 million trees have died • Increase threat of wildfires • Impacts ecosystems o Animals/insects require the trees for nutrients/protection/etc.

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§ Reservoirs are drying up § Compared to now, the drought is gone for large areas of CA § Lots of precipitation in the winter of 2016/2017 § Buildup of snowpack US Drought going into previous winter o 33% chance of having a warmer winter o Areas are expected to have more precipitation than normal Based on temperature would you expect the change of drought conditions to increase or decrease? Why? o Increase o More evaporation o If it is a warmer than average winter, drought is more likely to expand over the winter because if temperatures are warmer, more evaporation

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Weather: The state of the atmosphere at a given time and place. This state is defined with respect to variables such as temperature, moisture, wind velocity, and barometric pressure (pic 1) Meteorology: The study of the atmosphere Climate: The meteorological conditions (temperature, precipitation, wind, etc.) that characteristically prevail in a particular region. Generalized weather variation for a given place. Can be thought of as “average weather” (pic 2) o Climate § Pressure and density decrease with height in the atmosphere § Pressure drives temperature change in the troposphere § Pressure profile § Average temperature profile >>>>>> • Changes based on day-to-day basis § What drives climate? • ** TEMPERATURE • The sun o Without solar radiation, the earths climate would be MUCH colder • Composition of our atmpsohere Atmospheric Composition o Changes from time to time

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o Mostly: § Nitrogen 78% § Oxygen 21% o Carbon Dioxide § Greenhouse gas § Climate Change § Currently 404 ppm o Changing amount of greenhouse gasses, changes amount of radiation hitting earth, changes climate Solar Radiation o Solar radiation is what heats our planet and impacts climate § Rotation around the sun in ellipse • Different radiation from sun in winter and summer § Seasons/seasonal changes in atmosphere • Due to tilt of axis § Temperature • Suns temperature is not constant o Changes in 11-year cycles Global Energy Budget o Climate is determined by flow of energy o 50% of radiation is absorbed by earth’s surface and emits it back to space o Greenhouse gases emit the radiation back down o surface ends up being warmer than what it got from the sun o Incoming energy equals outgoing energy, in general Climate Controls o Latitude: § Variations in the receipt of solar energy are largely a function of latitude • SEASONAL VARIATIONS:: § Farther you go to the poles, larger deviations in summer/winter temperatures • Equator: no difference in temperature in summer and winter § We get less o Land and Water: § Marine climates are considered mild § Continental climates tend to be much more extreme § Climate at coastline is different than climate in the middle of land • Land varies more than coast o Geographic positioning and prevailing winds: § The windward sides of continents are likely to have marine climates § Leeward sides are more likely to have continental climates § Drier area = more variations • DUE TO LESS WATER VAPOR

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o Mountains and Highlands / Altitude: § These topographic barriers trigger orographic precipitation o Ocean Currents: **** § Cold currents cause aridity and fog § Warm currents cause warmer air temperatures § East coast: warm current running up the coast § West coast: cool current running down the coast o Pressure and Wind Systems: § Latitudinal shifting of pressure belts is responsible for seasonal precipitation § ICTZ – precipitation forms § High Pressure – Clockwise § Low Pressure – counterclockwise Climate Classification o Koppen Classification: § This tool is based on mean monthly and annual temperatures and precipitation § Latitude and proximity to water are 2 factors to take into account when classifying § Criteria are unambiguous, simple to apply, and are realistic § Recognizes 5 principle climate groups § Subcategories based on amount of precipitation § KOPPEN SYSTEM: • A) Humid Tropical – (tropics) all months have a mean temperature greater than 18oC o Wet Tropics (Af, Am) § The mean temperature 25oC+ § Only cover about 10% of Earth’s land area § Total precipitation averages 200+ cm year § It is wet all year o Tropical Wet and Dry (Aw) § Often called a Savanna Climate § The rain forest gives way to a tropical grassland § It has distinct wet and dry seasons § Associated with Monsoon: • Alternating periods of rainfall and dryness are associated with the monsoon • Typically refers to wind systems and their seasonal reversal • High pressure of the oceans in summer results in wet conditions • High pressure over land in winter results in dry conditions • B) Dry – when evaporation exceeds precipitation (deserts, • mountain terrain) o LARGEST CATEGORY:: 30%

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o Yearly precipitation is less than the potential water loss by evaporation o Lack of convection, lack of clouds, lack of reflection radiated back to space o Precipitation: § BWh: precipitation greatest in winter § BSh: precipitation greatest in summer o West coast subtropical deserts: § These deserts are the Namib, Atacama, Sonoran, Sahara § Cold ocean currents just off shore have a dramatic influence on climate § These areas have cooler mean annual temperatures and smaller daily ranges o Mid-latitude desert (BWk) and steppe (BSk) § Mainly caused by rain shadows • Lee side of mountains § They have much lower winter temperatures and higher annual ranges of temperatures o Temperature: § A lack of clouds makes for a greater temperature range C) Humid midlatitude, mild winters – (sea regions) mean temperature of the coldest month is above -3oC and lower than 18oC o Humid Subtropical Climate (Cfa) – NEW YORK / LONG ISLAND § This climate is found on the eastern side of continents between 25o and 40o latitude § They have hot and humid summers and precipitation of 100+ cm § Four seasons § Most of east coast o Marine West Coast Climate (Cfb) § This climate is found on the western side of continents between 40o and 65o latitude § They have mild winters and cool summers with precipitation throughout the year o Dry summer subtropical (Mediterranean) climate (Csa, Csb) § These are typically located on the western sides of continents between latitudes 30o and 45o § Csa has warmer summers § Csb has cooler summers § Both average between 40 and 80 cm per year in precipitation and are considered subhumid

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D) Humid midlatitude, severe winters – mean temperature of the coldest month is less than -3oC and the warmest month is higher than 10oC o Humid Continental Climate (Df) § This is a land-controlled climate § Annual temperature ranges are great § Maximum precipitation occurs during summer o Subarctic Climate (Dfc, Dfd) § Often called the Taiga Climate § Characterized by long, bitterly cold winters, and short warm/hot summers § This climate has approximately 50 cm of precipitation per year E) Polar – summer-less, mean temperature of the warmest month is lower than 10oC, very little precipitation o Tundra Climate (ET) § Large portions are characterized by permafrost § This climate has small amounts of precipitation with a modest summer maximum § Has cool short summers (10oC) § Tundra’s can also occur at higher elevations o Ice-cap Climate (EF) § This climate has no monthly mean temperature above 0oC § The landscape is one of permanent ice and snow Highland o Temperature, precipitation, altitude o These mountain climates (at elevation) are cooler and usually wetter than those at low elevations

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Earth’s Spheres o The climate system involves exchanges of energy and moisture among 5 spheres § *** ALL SPHERES ARE CONNECTED § Geosphere: extends from surface to center § Atmosphere: Mostly within 20 miles of surface; protects; where weather occurs § Hydrosphere: oceans, lakes, rivers, glaciers § Biosphere: includes all life § Cryosphere: The Earth’s surface that is solid water The Climate System o Interaction between spheres

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Natural Causes of Climate Change (NON-ANTHROPOGENIC—human caused) o Plate Tectonics § Tectonic plates move very slowly and produce gradual changes § Pangea -> continent configuration we know today • Southern hemisphere -> Northern Hemisphere o Volcanic Activity § This material filters out solar radiation § Changes composition of atmosphere § Changes amount of radiation • Acts as a blanket § It also lowers the temperature in the troposphere • The Mount St. Helens eruption lowered the temperature 0.1oC • El Chichon, in 1982, lowered the temperature 0.3-0.5oC • Mount Pinatubo, in 1991, lowered temperature 0.5oC o Variations in Earth’s orbit § The Milankovitch mathematical model is based on several elements: • Variations in shape (eccentricity) of Earth’s orbit about the Sun • Changes in obliquity – that is, changes in the angle of the axis o Ellipse • Precession, the wobbling of Earth’s axis o *** ICE AGES COME FROM THE MILANKOVICH CYCLES o Solar variability § Sunspots are huge magnetic storms on the Sun’s Surface • They eject large numbers of particles that interact with gases in the Earth’s upper atmosphere • They are on, approximately, an 11-year cycle between high and low activity § Sunspots and Temperature • Low sunspot activity has been identified with colder periods in North America and Europe § Sunspots and Drought • Periods of drought in the western United States coincide with the 22-year magnetic cycle of the Sun

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What impacts climate change besides fossil fuels? o Urbanization o Deforestation o Pollution o Food consumption

11.19.19 • Climate Classification (Koppen System) o Distribution of land, clouds, mountains, water •

Human Causes of Climate Change o Addition of Carbon Dioxide to the atmosphere o Altering amount of ground cover: § Changes Albedo § Evaporation rates § Surface winds o Rising CO2 Levels: § Higher levels are due to burning fossil fuels and deforestation § Some of the excess is taken up by plans or is dissolved in the oceans o Role of Trace Gases: § Methane (CH4), nitrous oxide (N2O), and chlorofluorocarbons (CFCs) all absorb wavelengths of outgoing radiation from Earth • Called greenhouse gases because it warms (think of a greenhouse for plants)

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Global Temperature: o Are they changing? § YES • Temperature is getting colder in Canada, while other places are getting warmer

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How is Climate Change detected? o Proxy data comes from sea floor sediments, glacial ice, fossil pollen, and tree growth rings, as well as from historical documents o Paleoclimatology: § Scientists who analyze proxy data and reconstruct past climates are engaged in paleoclimatology o Sea Floor Sediment – a storehouse of climate data: § This sediment consists of dead, near-surface organisms that accumulate on sea floor o Oxygen-isotope analysis: § Measures the ratio between 16O (common) and 18O (heavier) in ocean water • There is more 18O in water during glacial times • There is more 16O in water during interglacial times o Climate change recorded in glacial ice: § Scientists collect ice cores with a drilling rig § Ice cores contain a detailed record of changing air temperatures and snow fall § They also contain air bubbles trapped in the ice, which contain a record of variation in atmospheric (composition?)

o Tree rings § Provide archives of environmental history § Dendrochronology is the dating and study of tree rings • Thick tree rings indicate favorable growth conditions • Thin tree rings indicate unfavorable conditions o Other types of proxy data: § Analyzing fossil pollen makes it possible to obtain high-resolution records of vegetational changes in an area § Corals exhibit seasonal growth bands • The accuracy and reliability of climate data extracted from corals has been established when compared to recent instrumental records § Historical data sometimes will contain information, but do not readily lend themselves to climate analysis •

Where do increased greenhouse gases come from?

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Natural Variability (Internal aspect of climate system): o We have already looked at this from the general circulation view:

o Ocean currents: § Ocean currents have an important impact on climate, which helps maintain the Earth’s heat balance • Cold currents offshore result in a dry climate

• Warm offshore current produces a warm moist climate Upwelling, a wind-induced vertical movement, is the rising of cold water from deeper layers to replace warmer surface water • It occurs where winds blow parallel to the coast toward the equator o El Nino and La Nina: § Occur when general circulation in atmosphere change for ANY reason • Not well understood why these occur or how to predict them § Gradient in sea surface height § NOT THE WARMEST WATER; JUST WARMER THAN NORMAL § El Nino is a gradual warming of eastern pacific waters in December or January • Winds from east to west • Weaker winds • Decrease in convection (where water is colder) • Increase in convection (where water is warmer) § La Nina is the opposite of El Nino and refers to colder-than-normal ocean temperatures • More wet • Stronger winds • Can change amount of storms that form in the north atlantic ocean o Increase amount of shear in north Atlantic (bad for hurricanes) § IMPACT OF EL NINO: • It is noted for its potential catastrophic impact on weather and economies of Chile, Peru, Australia, and other countries o Arid areas can receive a lot of precipitation o A change in surface water temperature can kill fish • El Nino has been recognized as part of the global atmospheric circulation pattern § IMPACT OF LA NINA: • La Nina is also an important atmospheric phenomenon • In western pacific, wetter than normal conditions occur • More frequent hurricanes in Atlantic § Southern Oscillation: • This is the seesaw pattern of atmospheric pressure between the eastern and western pacific • Winds are the link between pressure changes and the ocean warming and cooling associated with El Nino and La Nina §

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Broader Impacts of El Nino are known as Teleconnections

Climate-Feedback Mechanisms o When one or more component of the climate system is altered, scientists must consider many possible outcomes o TYPES OF FEEDBACK MECHANISMS: § The effects of positive-feedback mechanisms reinforce the initial change § Negative-feedback mechanisms produce results that are just opposite of the initial change o Ice – Albedo Feedback § What happens to the albedo as ice melts? § Positive feedback § Amplifies change (sound) § Between Atmosphere and cryosphere/hydrosphere o Cloud Feedback § How do clouds change? § Can be positive OR negative § Damping system § NEGATIVE EX:: • If greenhouse gasses warm the earth, we get more evaporation. More water in atmosphere = more clouds o Cloud reflects more sunlight back to space

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^This picture has a negative feedback o Water Vapor Feedback § What happens to water vapor in the atmosphere as the temperature warms? § What does water vapor do in the atmosphere? § Increase CO2, more radiation emitted from earth absorbed by mores gases in the atmosphere and then is emitted back to earth • Increase temperature o Increase evaporation, increase water vapor in atmosphere o WATER VAPOR IS A GREENHOUSE GAS ∴MORE GREENHOUSE GASSES IN ATMOSPHERE § Main driver of evaporation: surface temperature § Positive feedback § PIC >>>>>> o Radiation Feedback § Does the amount of radiation the Earth emits change as it warms? § Objects emit radiation based on temperature § If surface temperature increases, amount of radiation increases • More radiation going back to space 11.21.19 •

REMINDER::: o Saturation Vapor Pressure is the equilibrium where vapor pressure is formed (through evaporation) and removed (via condensation) at the same rate § Dependent on the temperature of the warm air § If you increase temperature of a system (even the Earth), you will increase evaporation o Gases in the atmosphere § What is the role of gases in the atmosphere? • They heat the atmosphere through their interaction of incoming and outgoing radiation

Recent Climate Change o Observed change over the last 130+ years o Arctic changes the fastest because of the ice-albedo feedback • Context: o Earth has warmed over at least the last ~100 years o Earth’s axis changes evert 21000 cycles (aprox) o Warms quicker than it cools o Since the dinosaurs died… § Our present climate is relatively cold and highly variable (Milankovitch Cycles) § Studies portray tropical artic in distant past • How do we project climate change? o Computer models of Climate: Important yet imperfect tools § Mathematical models are simplified versions of the real climate § Earth’s climate system is very complex § It is way too difficult to model all variables § PROJECTED 6 DEGREES § Needs to capture all feedbacks • Climate models o Used to understand the past • Projected Changes of climate change o Higher maximum temperatures; more hot days and heat waves over nearly all land areas (virtually certain) o Higher minimum temperatures; fewer cold days, frost days, and cold waves over nearly all land areas (virtually certain) o Frequency of heavy precipitation events over most areas (very likely) o Increases in area affected by drought (likely) o Increases in tropical cyclone activity

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Local Impacts of Climate Change o Sea-level Rise § Dependent on locality and coastline § Due to: • Result of THERMAL EXPANSION OF WATER o Warming of water • Ice caps melting • Glaciers melting • Tide (locally) o Changing Arctic § Decrease in sea ice extent Climate Change: o The scientific foundation of our understanding of the Earth’s Climate is based on fundamental principles of the conservation of energy, momentum, and mass o The scientific foundation of our understanding of the Earth’s climate is based on an enormous and diverse number of observations o Based on the scientific foundation of our understanding of the Earth’s climate, we predict with virtual certainty: § The average global temperature of the Earth’s surface will continue to rise because of the continued increase of human-caused addition into the atmosphere of gases that hold the heat close to the surface § Historically sta...