Unformatted text preview: The Atmosphere The Weather vs. climate Weather Weather: Weather: The state of the atmosphere at a given time (hour to hour or day to day) given Climate: A description of aggregate Climate: weather conditions, based on observations that take place in a region over a period of years over Basic elements of weather & climate climate Air temperature Humidity Type and amount of cloudiness Type and amount of precipitation Air pressure The speed and direction of the wind Composition of the Atmosphere Composition Nitrogen: 78% Oxygen: 21% Other gases 1% Carbon dioxide Carbon Formula: Absorbs CO2 heat energy radiated by earth Influences heating of the atmosphere Water vapor Water Formula: Varies H 2O from 0-4% composition Source of all clouds and precipitation Absorbs or release heat energy (latent Absorbs heat) heat) Ozone Ozone Formula: O3 Allotrope of oxygen Highly toxic Ozone is concentrated in the stratosphere Ozone absorbs harmful ultraviolet Ozone radiation from the sun radiation Ozone is being slowly depleted from the Ozone atmosphere due to use of chlorofluorocarbons (CFC’s) chlorofluorocarbons Structure of the Atmosphere Structure
Four layers of the atmosphere 1) Troposphere 2) Stratosphere 3) Mesophere 4) thermosphere Structure of the Atmosphere (cont.) (cont.) 50% 50% of our atmosphere lies below an altitude of 3.5 miles above the Earth’s surface surface Troposphere Troposphere The bottom layer of the atmosphere Virtually all life exists in this layer This layer is responsible for all our This weather weather Temperature of troposphere decreases Temperature with increasing altitude (3.5oF per 1000 ft.) with Outer boundary is called the tropopause Stratosphere Stratosphere This layer lies beyond the tropopause Temperature remains constant to height of Temperature 13 miles, then the temperature will gradually increase gradually Ozone is concentrated in this layer Outer layer is called the stratopause Mesosphere Mesosphere Temperature Temperature decreases gradually with increasing height until one reaches the mesopause mesopause At that point temperature reaches around 90oC (-130oF) Thermosphere Thermosphere Layer extends beyond the mesopause Temperature rise rapidly and are very high Temperature (>1000oC or 1800oF) (>1000 Earth-Sun relationships Earth-Sun Virtually Virtually all the energy that drives the earth’s weather comes from the sun earth’s Solar energy is not evenly distributed over Solar the earth’s surface. Amount of energy depends on latitude and season depends Wind and currents are due to unequal Wind heating of the earth heating Earth’s motions Earth’s Two principal motions: 1) rotation: Spinning of the earth about its axis axis 2) revolution: movement of the earth about the sun. about At At any moment, half of the earth is experiencing daylight, the other half darkness. darkness. The line separating the lighted half from The the dark half is the circle of illumination the Seasons Seasons Seasons Seasons are based on two contributing factors: factors: a) length of daylight a) b) angle of the sun b) The The greater the angle of the sun, the more concentrated to the Earth’s surface. concentrated The sun’s angle is highest in summer, and The lowest in the winter lowest When When the sun orbits the earth, the Earth tilts 23 1/2 degrees from the perpendicular perpendicular This is called the inclination of the axis This inclination During During the summer solstice (June 21), the Northern Hemisphere is leaning 23 ½ degrees towards the sun towards During the winter solstice (December 21), During the Northern Hemisphere is leaning 23 ½ degrees away from the sun from During During the autumnal and spring equinoxes (September 22 & March 21), the Earth is tilted 0o from the sun. tilted Facts about the summer solstice Facts Occurs June 21 or 22 Vertical rays of the sun are striking the Vertical Tropic of Cancer (23 ½ north latitude) Tropic Northern Hemisphere are experiencing the Northern greatest length of daylight greatest Locations north of the Tropic of Cancer Locations are experiencing the highest noon Sun angles angles The The farther you are north of the equator, the longer the period of daylight, until the Arctic Circle is reached, where the daylight lasts for 24 hours lasts The The opposite occurs during the winter solstice solstice Heat & Heat transfer Heat Heat: Heat: Form of energy that moves from a warmer body to a cooler body warmer If two objects of unequal temperature are If in contact with each other, heat will travel from the warmer body to the cooler body. from The temperature of the warmer will The decrease, temperature of the cooler body will increase will Mechanisms of Heat Transfer Mechanisms
1) 2) 3) Conduction Convection radiation Conduction Conduction Transfer Transfer of heat through matter by molecular activity molecular Transfer occurs by collisions from one Transfer molecule to another molecule Conduction of heat varies from one Conduction material to another material Metals are the best heat conductors Convection Convection Transfer Transfer of heat by mass movement or circulation within a substance circulation Convection primarily takes place in fluids This is the type of heat transfer that This primarily occurs in the atmosphere primarily Radiation Radiation Transfer Transfer of energy through a vacuum or space space Solar energy reaches our planet by way of Solar radiation radiation Forms of Radiation Forms
1) 2) 3) 4) 5) 6) Visible Infrared Ultraviolet X-rays Microwaves radiowaves Radiation (cont.) Radiation All All these radiations constitutes a collection of radiations called an electromagnetic spectrum spectrum Each of these radiations have a Each characteristic wavelength characteristic Wavelength: Distance from one crest to Wavelength: the next the Visible radiation Visible Radiation which can be seen by our eyes. Visible radiation can be broken down into Visible its seven colors (what are the colors?) its Infrared radiation Infrared Radiation Radiation is longer in wavelength than visible light visible Lies above the red region of the visible Lies spectrum spectrum Responsible for heat radiation Ultraviolet radiation Ultraviolet Shorter wavelength than visible radiation Lies below the violet region of the visible Lies spectrum spectrum Primary source of radiation from the sun. Primary Responsible for sunburn Responsible Basic Laws of Radiation Basic
1) 2) 3) 4) All objects give off radiation, regardless All of temperature of Hotter objects give off more radiation Hotter than colder objects than The hotter the radiating body, the shorter The the wavelength of maximum energy the Objects that are good absorbers are also Objects good emitters as well good Fate of incoming solar radiation Fate When When radiation strikes an object, three possible outcomes can occur: possible 1) Radiation can be absorbed by the object 1) 2) Radiation can be transmitted (go through) the object through) 3) Radiation can be reflected (bounced off) an object off) Solar radiation and our Earth Solar About About 50% of the solar energy reaching the atmosphere is absorbed by the Earth’s surface surface About 30% is reflected back into space by About the atmosphere, clouds, and other reflective surfaces reflective About 20% is absorbed by clouds and the About atmosphere’s gases atmosphere’s Reflection Reflection About About 30% of the solar energy reaching the outer atmosphere is reflected back to the space the This fraction of total radiation that is This reflected is called albedo reflected Absorption Absorption Gases are selective absorbers Nitrogen is a poor absorber of solar Nitrogen radiation radiation Oxygen removes most of the shorter Oxygen wavelength ultraviolet radiation and ozone absorbs most of the ultraviolet rays from the stratosphere the Albedo Albedo The The fraction of radiation that is reflected by the earth’s surface the Albedo of the Earth, as a whole is 30% Albedo varies on Earth from place to place Albedo and from time to time and Factors affecting albedo Factors Amount of cloud cover Sun’s angle Presence of particulate matter Nature of the Earth’s surface Scattering Scattering Occurs Occurs when a beam of light produces a larger number of weaker rays larger The weaker rays travel in all directions Scattering of light accounts for the Scattering blueness of our sky blueness The greenhouse effect The This This is the increase in the temperature of a planet’s atmosphere caused when infrared-absorbing gases are introduced into the atmosphere into 50% 50% of the solar energy that strikes the Earth’s surface is absorbed Earth’s Most of this radiation is radiated skyward The radiation that the Earth gives off has The longer wavelengths than solar radiation longer Greenhouse gases Greenhouse Carbon dioxide Water vapor Principles behind the greenhouse effect effect Short Short wavelength radiation from the sun passes through the atmosphere and is absorbed by the Earth’s surface absorbed Energy is emitted from the surface as Energy long-wavelength radiation long-wavelength Much of this radiation is absorbed by Much certain gases in the atmosphere certain Radiation absorbed by the atmosphere is Radiation reradiated skyward reradiated Without Without the greenhouse effect, life on our planet will not exist planet Water vapor Water Water Water vapor is an excellent absorber of long-wavelength (infrared) radiation long-wavelength Water vapor absorbs five times as much Water terrestrial radiation than all other gases combined combined The concentration of water vapor The increases with altitude Carbon dioxide Carbon Carbon Carbon dioxide, like water, contributes to the greenhouse effect the Carbon dioxide is an important heat absorber A change in the atmosphere’s carbon change dioxide content can influence air temperature temperature Global warming Global Earth’s Earth’s industrialization is fueled by the burning of fossil fuels. burning Sources of fossil fuels: coal, natural gas, Sources petroleum. petroleum. Contributors of carbon dioxide release release Burning of fossil fuels The clearing of forests (deforestation) Out of all the carbon dioxide available, 4550% remains in the atmosphere The atmosphere’s response The The The global average temperature increased by about 1oF by The 1990s was the warmest decade, in The recent memory recent Possible consequences Possible Probable rise in sea levels Potential weather changes Stronger tropical storms Increases in the frequency of heat waves Increases and droughts and Temperature controls Temperature
A factor that causes temperature to vary factor from place to place and from time to time from Factors that cause temperatures to vary vary Differences Differences in receipt of radiation due to latitude latitude Unequal heating/cooling of land and water Altitude Geographic position Ocean currents ...
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This note was uploaded on 12/25/2010 for the course ESC 1000 taught by Professor Faculty during the Fall '10 term at FAU.
- Fall '10