Week 3 Solar Radiation Geo 114 PDF

Insolation & Temperature  Temperature: A Measure of Heat Energy is the capacity to do work May exist in many forms (light, thermal, kinetic, potential, nuclear, etc.) Heat is one form of energy Temperature is an expression of the degree of hotness or...

Insolation & Temperature  Temperature: A Measure of Heat Energy is the capacity to do work May exist in many forms (light, thermal, kinetic, potential, nuclear, etc.) Heat is one form of energy Temperature is an expression of the degree of hotness or coldness of a substance https://oxscience.com/wp- content/uploads/2020/07/dif ference-between-heat-and- temperature-min.png Measuring Temperature 1. Fahrenheit Scale 2. Celsius Scale 3. Kelvin Scale http://www.livephysi cs.com/media/stories /tools/thermodynami cs/xtemperature- scales.png.pagespeed.ic.ZrXYTiaD9i.png Sensible temperature / Effective temperature: the temperature we feel in response to the total condition of the air around us; may or may not be representative of the actual air temperature Wind-chill index and Heat index https://www.wfxrtv.com/wp- content/uploads/sites/20/2022/ 07/WeatherShareSnapShot- 16.jpg?w=1920  SOLAR ENERGY & INSOLATION Sun supplies the energy that drives most atmospheric processes Radiant energy from Sun is in the form of electromagnetic waves and these do not require a medium to pass through Electromagnetic waves are classified on the basis of wavelength Wavelengths vary Various lengths make up the electromagnetic spectrum https://www.qrg.northwestern.edu/projects/vss/ docs/media/Communications/wavelength.gif  THE ELECTROMAGNETIC SPECTRUM Electromagnetic radiation of all wave lengths comprises what is called the electromagnetic spectrum Wavelengths vary from very short wavelengths of gamma rays to long wavelengths such as radio waves https://cdn1.byjus.com/ wp- content/upl oads/2020/ 11/electrom agnetic- waves.png  Shortwave vs Longwave Radiation Solar radiation is almost completely in the form of visible light (ultraviolet and short infrared radiation) This is referred to as shortwave radiation Radiation emitted by Earth (terrestrial radiation) is entirely the in thermal infrared portion of the spectrum This is referred to as longwave radiation  WARMING AND COOLING OF THE ATMOSPHERE 1. Radiation Electromagnetic energy is emitted from an object Refers to the flow and emission of electromagnetic energy All objects emit electromagnetic radiation The hotter the object, the more intense its radiation The hotter the object, the shorter the wavelengths of that radiation Hot bodies radiate mostly short wavelengths of radiation; cooler bodies radiate mostly long wavelengths Blackbody radiator: a body that emits the maximum possible radiation at all wavelengths https://www.e- education.psu.edu/meteo300/ sites/www.e- education.psu.edu.meteo300/f iles/images/lesson6/solarrad1. gif 2. Absorption Assimilation of electromagnetic waves which strike an object Different materials have different absorption capabilities A good radiator is a good absorber A poor radiator is a poor absorber 3. Reflection The ability of an object to repel electromagnetic waves that strike it If a wave is reflected it cannot be absorbed A good absorber is a poor reflector A poor absorber is a good reflector Albedo: overall reflectivity of an object or surface, usually described as a percentage https://cleantechnica.com/files/2019/02/Typical-albedo-values-for-Earth-surfaces.-Credit-Steven-Earle.png 4. Scattering Gas molecules and particulate matter deflect light waves and redirect them There is a change in the direction of the light wave, but no change in wavelength Some waves back-scattered into space (does not reach Earth) Many waves continue through the atmosphere in random directions and strike the surface as diffuse radiation The amount of scattering depends on wavelength, size, shape and composition of the molecule or particulate Shorter wavelengths are more readily scattered than longer wavelengths by atmospheric gases Rayleigh Scattering: shortest wavelengths of visible light (violet and blue) scattered more easily than longer wavelengths (orange and red) in all directions by gas molecules (sky is blue) Red and orange sunsets when Sun is low in sky Mie Scattering: large quantities of particulates (aerosols) more equally scatter all wavelengths of visible light (sky looks gray) A consequence of scattering, especially Raleigh Scattering, is the intensity of solar radiation striking the surface of earth is diminished https://i.stack.imgu r.com/uoXQb.gif 5. Transmission Incoming radiation passes through a surface or object and is neither absorbed nor reflected Earth materials are generally opaque and poor transmitters of insolation (eg. Rock, soil) Water transmits sunlight well Transmission ability of a medium depends on the wavelength of radiation Glass has high transmissivity for shortwave, but not longwave radiation The Greenhouse Effect Greenhouse gases transmit incoming shortwave radiation from the Sun, but do not easily do this for longwave terrestrial radiation Most important greenhouse gases are water vapour, carbon dioxide and methane Other trace gases and some clouds also play a role The Greenhouse Effect is one of the most important warming processes in the troposphere https://upload.wiki media.org/wikipedi a/commons/8/8e/E arth's_greenhouse_ effect_(US_EPA,_20 12).png 6. Conduction The transfer of heat from one molecule to another without changes in their relative positions When two molecules of unequal temperature are in contact, energy transfers from the hotter to the cooler until they reach the same temperature Most metals are excellent conductors; earth materials and air are poor conductors Earth’s land surface warms rapidly during the day and some warmth is transferred away from the surface by conduction Only the air layer touching ground is warmed very much Moist air is a slightly more efficient conductor than dry air 7. Convection Energy is transferred from one point to another mainly by vertical circulation of a fluid or air Movement of warmed molecules from one place to another The atmosphere frequently develops convective patterns, referred to as convection cells https://sciencenote s.org/wp- content/uploads/20 22/09/Types-of- Heat-Transfer.png 8. Advection Occurs when the primary direction of energy transfer is horizontal The horizontal component of air movement in a convection cell is called advection https://meteo rologyman.fil es.wordpress. com/2014/01 /heattransfer. png 9. Adiabatic Cooling and Warming When air ascends or descends, its temperature changes Rising air expands (less air above it; less pressure) and sinking air is compressed (more air above; more pressure) Adiabatic cooling: expansion occurs in rising air; this is a cooling process Adiabatic warming: compression occurs in descending air; this is a warming process Adiabatic cooling important in cloud formation and precipitation and adiabatic https://slideplayer.com/ warming has an opposite effect slide/16538958/96/imag es/5/Adiabatic+cooling% 2Fheating.jpg 10. Latent Heat A phase change of water (ice to liquid to water vapour etc.) involves an exchange of energy called latent heat Most common phase changes are evaporation (where latent heat energy is stored) and condensation (where latent heat energy is released) Evaporation is a looking process and condensation is a warming process Energy is transferred from one place to another in the atmosphere through movement and phase changes https://images.slidepl ayer.com/19/5768010 /slides/slide_20.jpg  EARTH’S SOLAR RADIATION BUDGET Long-term energy balance There is a balance between the total amount of energy received by Earth and the atmosphere and amount returned to space  Most of the insolation that reaches the upper atmosphere does not warm it directly About 31 units reflected or scattered back in space (Earth’s albedo is about 31%) 24 units warm the atmosphere directly 3 units of radiation (UV spectrum) absorbed by ozone layer 21 units absorbed by gases and clouds About 45 units of insolation transmit through atmosphere to Earth’s surface and is absorbed, warming the surface About 4 units conducted from surface to atmosphere and dispersed by convection Some energy is transferred via latent heat in water vapour and released when condensation occurs (19 units) Greenhouse gases absorbed about 14 units of energy About 8 units of energy, as longwave radiation, transmits through the atmospheric window  VARIATIONS IN INSOLATION BY LATITUDE AND SEASON 1. Angle of Incidence (the angle at which rays from the Sun strike Erath’s surface) is the primary determinant of the intensity of solar radiation received at any spot on Earth 2. Atmospheric obstruction: obstructions such as clouds, particulate matter and gas molecules reduce the intensity of Sun’s energy The attenuation (weakening) of radiation varies by time and place according to the amount of atmosphere through which radiation passes and the transparency of the air The distance a ray of sunlight travels through the atmosphere (path length) is determined by the angle of incidence High-angle ray has a shorter course through atmosphere than longer one A tangent ray (incidence angle of 0 degrees) must pass through nearly 20 times more atmosphere as a vertical ray 3. Day length: longer days allow more insolation and eventual absorption; in middle and high latitudes, day length varies with resulting variations in insolation (more in summer; less in winter) https://conten t.meteoblue.c om/en/researc h- education/edu cational- resources/met eoscool/gener al-climate- zones/Dayleng th_lightbox.jpg 4. Latitudinal Radiation Balance AVERAGE WORLD SOLAR RADIATION https://i.pini mg.com/orig inals/7b/58/ 0d/7b580d6 ca1f9a81f9f 1ba0e4f88b 2bce.gif  LAND AND WATER TEMPERATURE DIFFERENCES Warming of land and water surfaces Land heats up and cools faster than water Differences in heating and cooling are the result of: 1. Specific heat – water has a higher specific heat than land 2. Transmission – water is a better transmitter of radiation than land 3. Mobility – water is highly mobile and turbulent mixing and ocean currents disperse the energy both broadly and deeply 4. Evaporative cooling – unlimited availability of moisture on a water surface (more evaporation and cooling) https://image2.slideserve.com/5350225/land- water-heating- differences6-l.jpg  Implications of Contrasts between Land and Water Cooling and Warming Rates 1. The hottest and coldest areas of Earth are in the interiors of continents, distant from the influence of the oceans A continental climate experiences greater seasonal extremes of temperature than a maritime climate Oceans moderate coastal and nearby climates https://www.climatestotr avel.com/images/charts/D allas-United-States.png 2. Hemispheric differences – More land is in the Northern than Southern Hemisphere; the land hemisphere (Northern) has greater temperature extremes https://qph.cf2.quorac dn.net/main-qimg- c24d42c36c5f664e827 2c0413ee218a1-lq  GLOBAL ENERGY TRANSFER Energy transfer keep the tropics and poles from extremely hot and cold temperatures Circulation patterns in the atmosphere and oceans shift some of the warmth of the low latitudes toward the high latitudes and moderate the warmth of low latitudes and cold of the high latitudes Seventy-five to eighty-five percent of all horizontal energy transfer is accomplished by atmospheric circulation  OCEANIC CIRCULATION Winds disturb the surface of the ocean with swells and waves Wind also propels the surface of theater to move forward in the form of a current Surface ocean currents can flow at 1 – 2 percent of wind speed Wind blowing over the surface of the water is the principal force driving the major surface ocean currents Energy stored in the oceans affects atmospheric circulation Ocean Circulation Patterns All oceans interconnected Within each ocean basin there is a similar pattern of surface current flow based generally on the prevailing winds Pattern is of elliptical, elongated east-west loops (gyres) centered at about 30 degrees (except Indian Ocean – centered at equator) On the equatorward side of each gyre is an Equatorial Current propelled by the Trade Winds Near the western margin of each ocean basin currents curve to the east, propelled by Westerly Winds At the eastern edges of the basins they curve back toward the equator The movement of the currents is also influenced by the Coriolis Effect OCEANIC CIRCULATION https://upload.wikimedia.org/wikipedia/commons/9/9b/Corrientes-oceanicas.png  WARM AND COOL OCEAN CURRENTS Each major currents is either warm or cool (cold) Low-latitude currents have relatively warm water Poleward-moving currents carry relatively warm water toward higher latitudes High-latitude currents in the Northern Hemisphere gyres carry warm water to the east High-latitude currents in the Southern Hemisphere carry cool water to the east Equatorward-moving currents carry cool water toward the equator Poleward-moving warm currents off the east coast of continents tend to be narrower, deeper and faster-flowing than cool currents; this is called western intensification (it occurs on western coasts at mid-latitudes Other Patterns: The northwestern portions of the Northern Hemisphere ocean basins receive an influx of cool water from the Arctic Ocean Wherever an equatorward-flowing cool current pulls away from a subtropical western coast, there is a persistent upwelling of cold water There is a deep ocean circulation pattern – global conveyor belt circulation – that influences global climates  VERTICAL TEMPERATURE PATTERNS Environmental Lapse Rate Generally, there is a general decrease in temperature with increasing altitude in the troposphere; however, there are exceptions Some reasons for variations in temperature decline are according to season, time of day, and amount of cloud cover The observed trend in vertical temperature change in the atmosphere is called the environmental lapse rate When measuring the lapse-rate temperature change, only the thermometer is moved (the air is not moving; if air moves vertically it will cause adiabatic temperature change Average Lapse Rate The average rate of temperature change is about 6.5 degrees C per 1000 meters (3.6 degrees F per 1000 feet)  TEMPERATURE INVERSIONS A condition in which the temperature increases with increasing altitude Usually common in the troposphere, but of short duration and restricted depth https://www.drishtiias.co m/images/uploads/159869 4790_image4.png Surface Inversions 1. Radiation inversion: cold inter night the land surface rapidly emits longwave radiation into a clear, calm sky; the cold ground cools the air above and the lowest few hundred meters of the troposphere become colder than the air above; prevalent in high latitudes 2. Advectional inversion: horizontal inflow of cold air into an area; commonly produced by cool maritime air blowing into a coastal area 3. Cold-air-drainage inversion: cooler air slides down a slope into a valley displacing slightly warmer air; commonly occurs at mid-latitudes during winter  Radiation Inversion Advectional Inversion https://www. http://www.csun.edu/~h thephysicale mc60533/CSUN_103/weat nvironment.c her_exercises/soundings/s om/Book/te mog_and_inversions/Inve mperature/r rsions_files/image002.jpg adiation_inv ersion.png Cold-air-drainage Inversion Upper-air inversions Temperature inversions far above the ground surface are usually the result of air descending from above These are subsidence inversions and are usually associated with high-pressure conditions in subtropical latitudes  GLOBAL TEMPERATURE PATTERNS Isotherms are lines joining places of equal temperature Seasonal Patterns Isotherms follow the changing balance of insolation during the year Isotherm shift is more pronounced at high latitudes and over continents Isotherms are more tightly packed in winter (there is a greater contrast in radiation balance in winter) Coldest places are over landmasses in the higher latitudes Highest temperatures are over the continents at subtropical latitudes https:// Large seasonal variations in temperature in the media.c heggcd n.com/ interiors of high-latitude continents media/ 17c/s84 Continental areas generally experience greater 9x1024 /17c6d 94b- ranges than equivalent oceanic latitudes 778c- 4054- Average temperatures fluctuate slightly from ad31- f037758 f4017/p season to season in the tropics hpDJCd qx.png  Major Controls of Temperature 1. Altitude 2. Latitude 3. Land-water contrasts 4. Ocean currents CLIMATE CHANGE – GLOBAL WARMING https://ane4bf-datap1.s3-eu-west- https://assets.weforum.org/editor/ 1.amazonaws.com/wmocms/s3fs- UrFYyXbYOXM- public/ckeditor/files/Picture1_20.png 7XZGRvaHQkQu9ZX_HNu9omyb8Xt ?xgPgX8oYzDtzAFvgz7Cc3zvbz.YvOaH papw.png 4 https://imageio.forbes.com/sp ecials- images/imageserve/629c7ef77 e1b1a5c654fcbbb/NOAA- carbon-dioxide- level/960x0.jpg?height=535&w idth=711&fit=bounds https://www.noaa.go v/sites/default/files/ 2022- 04/ch4_trend_all_gl_ 20220405_0.jpg