Presentation on theme: "Air Pollution, Climate Change and Ozone Depletion"— Presentation transcript:
1Air Pollution, Climate Change and Ozone Depletion
2CLIMATE: A BRIEF INTRODUCTION Weather is a local area’s short-term physical conditions such as temperature and precipitation.Climate is a region’s average weather conditions over a long time.Latitude and elevation help determine climate.The two most important factors are temperature and precipitation.
3Earth’ climate system distributes heat & precipitation over time, creating climate Creates “weather” – day-to-day winds, clouds, rains, storms, heat waves, droughts, etc
4Earth’s climate system is composed of atmosphere/ocean interactions (driven by sun)
5Masses of air and water transfer solar energy through circulation/convection
6Solar Energy and Global Air Circulation: Distributing Heat Global air circulation is driven by the uneven heating of the earth’s surface by solar energy, seasonal changes in temperature and precipitation:Angle of raysSurface areaReflective surfaces
7VERY IMPORTANT: What causes the seasons? The ANGLE of the sun’s rays.Direct sunlight = summerDirect = more sunlight in a smaller area more heat storedIndirect sunlight = winterIndirect = sunlight spread over larger area less heat stored
8AlbedoThe higher the albedo of a surface, the more sun that is reflected and the less heat storedThe lower the albedo of a surface, the more sun that is absorbed and the more heat stored.
9Core Case Study Blowing in the Wind: A Story of Connections Wind connects most life on earth.Keeps tropics from being unbearably hot.Prevents rest of world from freezing.Figure 5-1
10Air Pressure Definition Air pressure is pressure exerted by the weight of Earth’s atmosphere. At sea level it is equal to pounds per square inch.A barometer is used to measure atmospheric pressure.
11Air Pressure Pressure Gradient Changes from high to low. On a map there is an arrow to show this. A higher pressure gradient means stronger winds (the isobars on a weather map would be drawn closer together).
12WindCauseWind is caused by the pressure gradient force. High pressure means more air, and low pressure means less air. The air moves from high to low, causing wind.
13Wind The Coriolis Effect Forces in the atmosphere, created by the rotation of the Earth on its axis, that deflect winds to the right in the N. Hemisphere and to the left in the S.Hemisphere.
15WindCoriolis EffectGlobal air circulation is affected by the rotation of the earth on its axis.Figure 5-4
16WindFrictionA combination of the pressure gradient force and the coriolis effect. Friction at the Earth’s surface causes winds to turn a little. Friction runs parallel to the isobar.
17WindUpper Level FlowThere is little friction up in the upper troposphere, driving surface features. Ex. during big thunderstorms, the wind in the upper level will tell which way the thunderstorm will move.
18WindCyclones(called hurricanes in the Atlantic and typhoons in the Pacific)Violent storms that form over warm ocean waters and can pass over coastal land.Giant, rotating storms with winds of at least 74 mph. The most powerful ones have wind velocities greater than 155 mph.
19Air Masses and Winds Polar vs. Tropical The atmosphere has three prevailing winds.Prevailing winds that blow from the North or South Pole are called Polar Easterlies.Winds that blow in the middle lattitudes (between 3o and 60 degrees) are called the WesterliesTropical winds that blow toward the equator are called Trade Winds.
21Continental vs. Maritime Air Masses and StormsContinental vs. MaritimeContinental fronts are generally cool and dry, whereas maritime (ocean) fronts are generally warm and moist. When these two air masses converge, the result is usually rain.
22Convection CurrentsGlobal air circulation is affected by the properties of air water, and land.Figure 5-5
23Convection CellsHeat and moisture are distributed over the earth’s surface by vertical currents, which form six giant convection cells at different latitudes.Figure 5-6
25Circulation Patterns Hadley Cells Trade Winds blow towards equator Warm moist air rises at the equator. RainAs air rises, it spreads out north & south, then cools and sinks at 30 degrees. DryThis is why most of the world’s deserts are found at 30 degrees.These are called the horse latitudes (3o degrees) because early settlers would get stuck here in their boats & couldn’t move. They would finally throw their horses overboard to lighten the load & get moving again.Trade Winds blow towards equator
26Circulation Patterns Ferrell Cells Warm air rises at about 60 degrees. Rainand sinks at around 30 degrees, dry, both north and south.Westerlies. Predominant winds in US
27Circulation Patterns Polar Cells Air rises at about 60 degrees. Rain floats north, and sinks at around 90 degrees, both north and south. DryEasterlies
29Circulation Patterns Convection Cells Ocean water transfers heat to the atmosphere, especially near the hot equator. (Trade winds)This creates convection cells that transport heat and water from one area to another.The resulting convection cells circulate air, heat, and moisture both vertically and from place-to- place in the troposphere, leading to different climates & patterns of vegetation.
30Sea, Land, Valley, & Mountain Breezes Sea - ocean-to-land breezes that occur during the day.Land - land-to-ocean breezes that occur at night.Valley - the wind blows from the plains into a valley between two mountains, the wind must divert into a smaller area. This causes high winds to form through the valleys.Mountain - Cool air coming from the top of the mountain sinks down on the eastern slope, causing increased winds on the mountain.
31Microclimate – Rain shadow effect Topography, water bodies and other local features create local climate conditions known as microclimate.For example mountains commonly result in high rainfall on the windward side and low rainfall in the rain shadow of the leeward side.We see this in LA: rainier on our side of the mountain – desert on the other side
32Microclimate – Rain shadow effect Topography, water bodies and other local features create local climate conditions known as microclimate.For example mountains commonly result in high rainfall on the windward side and low rainfall in the rain shadow of the leeward side.
33Ocean Currents: Distributing Heat and Nutrients Ocean currents influence climate by distributing heat from place to place and mixing and distributing nutrients.
34Ocean Currents: Distributing Heat and Nutrients Ocean currents influence climate by distributing heat from place to place and mixing and distributing nutrients.
36WeatherWeather is the condition in the atmosphere at a given place and time.Weather includes temperature, atmospheric pressure, precipitation, cloudiness, humidity, and wind.
37Local WeatherWeather is a local area’s short-term physical conditions such as temperature and precipitation.A weather front marks the boundary between two air-masses at different densities.A front is about km wide and slopes where warm and cool air masses collide.Weather is a local area’s short-term physical conditions such as temperature and precipitation.Climate is a region’s average weather conditions over a long time. Latitude and elevation help determine climate.Cold frontWarm front
38Weather Warm & Cold Fronts Warm Front - The boundary between an advancing warm air mass and the cooler one it is replacing. Because warm air is less dense than cool air, an advancing warm front will rise up over a mass of cool air.The leading edge of an advancing air mass of cold air. Because cool air is more dense than warm air, an advancing cold front stays close to the ground and wedges underneath less dense, warmer air. A cold front produces rapidly moving, towering clouds called thunderheads.
39Stationary & Occluded Front WeatherStationary & Occluded FrontA stationary front is a transitional zone between two nearly stationary air masses of different density.An occluded front is the air front established when a cold front occludes (prevents the passage of) a warm front.
40SeasonsThe Earth’s 23.5 degree incline on its axis remains the same as it travels around the sun. As the earth spins around the sun the seasons change.
41Solar year: the journey around the sun takes 365.2425 days. Earth-Sun-MoonEarth’s axis has a 23.5° tilt. This tilt always faces the same way, resulting in seasonal changes in sunlight and weather.Solar year: the journey around the sun takes days.Earth day: the Earth spins on its axis with respect to the stars once every 23h 56 min 4.09s (one sidereal day). The solar day, where the sun returns to its zenith, is exactly 24 hours.Lunar month: the time between successive full moons is 29.5 days, but the moons orbit around the Earth takes 27.3 days. Because the moon spins on its own axis once every 27.3 days, the same side of the moon always faces the Earth.All images: NASA
42Orbital CyclesThree long term cycles that the Earth goes through as it orbits the Sun are:Axial tilt: the axis of the Earth varies from 21.5° to 24.5°.Orbital eccentricity: Earth’s orbit varies from almost circular to elliptical.Precession: the movement of the axes in space causes them to describe a cone.All images: NASA
43Axial TiltThe tilt of the Earth’s axis ranges between 21.5° and 24.5°.This can have severe effects on the climate.An axis tilt of 21.5o allows more heating near the poles leading to a less extreme temperature gradient from pole to equator.When tilted at 24.5o the variation between winter and summer temperatures is much more pronounced.
44The opposite occurs in the southern hemisphere EccentricityWhen the Earth’s orbit is almost circular (as it is now), both summers and winters are relatively mild.This can trigger ice sheet build up as summer is not warm enough to melt winter snow.When Earth’s orbit is more elliptical, summers (as shown here) in the northern hemisphere can be relatively cold while winters are relatively warm.The opposite occurs in the southern hemisphereAll images: NASA
45PrecessionPrecession alters the orbital position of the summer and winter solstices.Around 13,000 years ago the southern hemisphere’s summer occurred in June.Global air circulation is affected by the uneven heating of the earth’s surface by solar energy, seasonal changes in temperature and precipitation
46Orbital CyclesThe changes in the tilting of the Earth’s axis, combined with precession and eccentricity can cause variations in the amount of solar radiation reaching the Earth’s surface.This can trigger the onset and recession of ice ages.Global air circulation is affected by the uneven heating of the earth’s surface by solar energy, seasonal changes in temperature and precipitation.
47Formation of the Atmosphere Most of the Earth’s early atmosphere was lost due to the vigorous solar wind from the early Sun.Continuous volcanic eruptions built a new atmosphere of:water vaporcarbon dioxidenitrogenmethane
48The AtmosphereThe mixture of gases known as air, protects life on Earth by absorbing ultraviolet radiation and reducing temperature extremes between day and night.The atmosphere is not static. Interactions involving the amount of sunlight, the spin of the planet and tilt of the Earth’s axis cause ever changing atmospheric conditions.Weather occurs in the troposphere. Gaseous water molecules held together by intermolecular forces cause the formation of clouds.The auroras occur in the thermosphere and are caused by interactions between the Earth’s atmosphere and charged particles streaming from the Sun.
50The atmosphere consists of several layers with different temperatures, pressures, and compositions.
51STRUCTURE AND SCIENCEThe atmosphere’s innermost layer (troposphere) is made up mostly of nitrogen and oxygen, with smaller amounts of water vapor and CO2.Ozone in the atmosphere’s second layer (stratosphere) filters out most of the sun’s UV radiation that is harmful to us and most other species.
52The Atmosphere Earth's atmosphere contains roughly: 78% nitrogen 20.95% oxygen0.93% argon0.038% carbon dioxideTrace gases1% water vapourThe Earth’s atmosphere (where pressure becomes negligible) is over 140 km thick. Compared to the bulk of the planet, this is an extremely thin barrier between the hospitable and the inhospitable.All images: NASA
53Troposphere 75% of mass of atmosphere 0 to 11 miles in altitude 78% nitrogen, 21% oxygenLocation of Earth’s weatherTemperature decreases with altitude until the next layer is reached, where there is a sudden rise in temperature
54Stratosphere 11 miles to 30 miles in altitude, calm Temperature increases with altitudeContains 1000x the ozone of the rest of the atmosphere; ozone forms in an equilibrium reaction when oxygen is converted to O3 by lightning and/or sunlight99% of ultraviolet radiation (especially UV-B) is absorbed by the stratosphere
55Mesosphere & Thermosphere 30 to 50 miles in altitudeTemperature decreases with increasing altitudeThermosphere50 to 75 miles in altitudeTemperature increases with increasing altitudeVery high temperatures
56Composition of the Atmosphere Components –Nitrogen 78%, Oxygen 21%, .93% argon, & .038% carbonLayers – troposphere, stratosphere, mesosphere, thermosphere, exosphere (extends from 310 miles to interplanetary space)
57Heat Transfer Conduction Radiation Warm air holds more moisture than cold air. During conduction, heat & moisture from the ocean or land moves into the atmosphere.Ex. cold air moving over warm water (like a lake), forming steam fog.RadiationRadiation drives weather. Heat from the sun warms the earth, which radiates the heat back into the atmosphere.ConvectionAir & water movement
58Natural Greenhouse Effect Some of the solar energy is trapped by molecules of greenhouse gases (water vapor, carbon dioxide, methane). Otherwise earth would be much colder
59Global WarmingConsiderable scientific evidence and climate models indicate that large inputs of greenhouse gases from anthropogenic activities into the troposphere can enhance the natural greenhouse effect and change the earth’s climate in your lifetime.
60N. hemisphere - CLOCKWISE S. hemisphere - COUNTER - CLOCKWISE Coriolis EffectThe spinning of the earth createsDifferent wind speeds at different latitudes (faster at equator, slower at poles)clockwise winds in the northern hemispherecounter clockwise winds in the southern hemisphereThis movement is called the Coriolis Effect.Watch: https://www.classzone.com/books/earth_science/terc/content/visualizations/es1904/es1904page01.cfm?chapter_no=visualizationN. hemisphere - CLOCKWISES. hemisphere - COUNTER - CLOCKWISE
61Coriolis and Convection cells With the Coriolis Effect, air still travels from the equator toward the poles, but due to the wind patterns, the 2 cells are broken into 6 global cells. Warm air rises in each cell and cools as it travels through the atmosphere, then sinks and warms as it travels across the land.Without the Coriolis Effect, air would travel in two large cells. The warm air at the equator would rise and move toward the poles. As it moved to the poles, it would cool and sink, then move back to the equator along land, warming as it moved.DOES NOT ACTUALLY HAPPEN
65Climate Changes with Elevation/Altitude As you go up in elevation:Less soil and less nutrients less plantsLess oxygenlower air pressure thinner atmosphere less organismsTemperatures decreasesMore UV rays – limits plant growth
66Ocean Currents: Transport nutrients and heat all over the globe Also called the Ocean Conveyor belt Driven mostly by:Wind/CoriolisTemperature gradients (colder water sinks) THERMOSalinity gradients (saltier water sinks) HALINE
67UpwellingOccur when ocean currents pull water from the deep ocean up to the surfaceUpwellings pull cold, nutrient rich water up to the surfaceGood for fishing: increases NPP as nutrients are often a limiting factor
68Gyres Direction driven by the Coriolis Effect and the continents 5 gyres that spin clockwise in the N. hemisphere and counter clockwise in the S. hemisphereRedistribute heat and nutrientsUpwellings occur along the west coasts of continents
69Ocean Currents There are two types of Ocean Currents: 1. Surface Currents / Surface CirculationThese waters make up about 10% of all the water in the ocean.These waters are the upper 400 meters of the ocean.Driven mostly by wind2. Deep Water CurrentsThese waters make up the other 90% of the oceanmove around the ocean basins by density and gravity.The density difference is a function of different temperatures and salinityThese deep waters sink into the deep ocean basins at high latitudes where the temperatures are cold enough to cause the density to increase.
71El Nino Southern Oscillation (ENSO): periodic weather pattern in the Pacific
72El Nino Southern Oscillation (ENSO) El Nino – warming event in the tropical Pacific OceanCaused by weak/no trade winds blowing WESTThe upwelling along the west coast of the Americas stopsOccurs in cycles every 2-7 yearsLa Nina – cooling event in the tropical Pacific OceanThe opposite end of the spectrum as an El NinoTrade winds and upwelling is strongBoth extremes cause extreme weather events globally
73ENSO effects – El Nino During an El Nino event Warmer ocean temps in the PacificWarmer and wetter in the western Americas from So. Cal south (Warmer and dryer in the Northwest US during winter and warmer and wetter in the summer)Suppresses hurricane activity in the Atlantic oceanMajor declining in fishing populations during an El NinoDrought in the western Pacific and Australia
74ENSO effects – La Nina During a La Nina event Pacific ocean temps are colder than normalDroughts along the west coast of the Americas (more snow in northwest US)Active hurricane season in the AtlanticMore rain in the Western Pacific and Australia