The Energy Cycle (Reading AK Chapter-2) Transferring Energy in the Atmosphere     Conduction: Requires Touching     Convection: Hot Air Rises     Temperature Advection: Horizontal Movement of Air     Latent Heating: Changing the Phase of Water     Adiabatic Cooling and Warming: Expanding and Compressing Air     Diabatic Cooling and Warming: Adding and Subtracting Heat     Radiative Heat Transfer: Exchanging Energy with Space    Sun and Seasons Radiative Properties of the Atmosphere Global Energy Budget  

Simple C to F conversion: Venus 457o C (855o F) No Atmosphere Facing the Sun (121degC) ((250F) C = 5 / 9 * (F – 32 ) F = (9 / 5 * C) + 32 K = 273.16 + C Mars 218K No Atmosphere Shadow and darkness (-157degC) (-250F) Temperature --Definition – A measure of the average kinetic energy of all particles within a sample. HEAT – Energy produced by motions of molecules and is the total kinetic energy of a sample. Simple C to F conversion: F = ( TempC + TempC ) –10% +32 Example: 30deg C 86 F = (30degC + 30DegC ) – 6 + 32

Energy Transfer The transfer of energy between two objects due to a difference in temperature is called HEAT energy. Methods of Heat transfer include Conduction, Convection, Advection, and Radiation Adiabatic heating/cooling are constant entropy processes and have no transfer of heat

Transferring Energy in the Atmosphere Conduction Requires Touching (land/ sea - air) Convection Vertical Movement--Hot Air Rises Temperature Advection Horizontal Movement Latent Heating Phase Change of Water (Diabatic) Adiabatic (heating-cooling) Expanding - Compressing Radiative Heat Transfer With Space

Conduction Convection Temperature Advection Latent Heating Adiabatic (heating-cooling) Radiative Heat Transfer

Surface and Air Temperature Cook an egg on sidewalk Turbulence is driven by the exchange in heat energy between the earth’s surface and the atmosphere. The surface heat flux in watts/m2 between the surface and air depends on the difference in temperature between the surface and air and on the prevailing wind speed. During the day, solar heating raises the surface temperature well above the air temperature, which leads to strong convective heating and turbulence. At night, Planck radiation to space cools the surface 5 to 10 C below the air above, which again produces turbulence. Twice per day the air and surface temperatures equilibrate and the surface heat flux drops to zero. D. L. Walters

Hot Enough to Fry an Egg Need a surface air temperature (2m) warmer than 35º C ~ 95 º F Egg white begins to coagulate at 62°C (144°F) while yolk begins to coagulate at 65°C (149°F). Note: This will take a few minutes

Midday Air Temperature-Desert The atmospheric temperature varies with time. This plot shows temperature fluctuation at 3 m and 33 m above the ground for a clear day around 1300 local time measured with a temperature probe that has a 10 ms time constant. The temperature fluctuations and average temperature are larger near the ground. Although the temperature fluctuations appear to be random, the low frequency, long time period disturbances dominate the changes. 15 min D. L. Walters

1km Vis at 1 min interval from GOES-8 Conduction Convection Temperature Advection Latent Heating Adiabatic (heating-cooling) Radiative Heat Transfer 1km Vis at 1 min interval from GOES-8 7204vis.avi http://www.shodor.org/metweb/

Measured Versus Calculated Variables 5 10 15 COLD WARM CO LD AD V WA RM AD V TEMPERATURE ADVECTION 500 mb 1000 mb

Conduction Convection Temperature Advection Latent Heating Adiabatic (heating-cooling) Radiative Heat Transfer

0 C Conduction Convection Temperature Advection Latent Heating Adiabatic (heating-cooling) Radiative Heat Transfer 0 C

Parcel does not exchange heat with its surroundings Conduction Convection Temperature Advection Latent Heating Adiabatic (heating-cooling) Radiative Heat Transfer Latent Heat release Atm Avg Lapse rate ~6.5 °C/km Expansion cooling  Compression warming Parcel does not exchange heat with its surroundings

I-80 Conduction Convection Temperature Advection Latent Heating Adiabatic (heating-cooling) Radiative Heat Transfer I-80

The Sun Solar Constant 1368 W/m2 Radiation – The transfer of energy through electromagnetic waves. Does not involve the movement of matter

E ~5.7x10-8 x T**4 Emax ~ 2900/T IR VIS Conduction Convection Temp Advection Latent Heating Adiabatic (heating-cooling) Radiative Heat Transfer Stefan-Boltzman Law (Sun 160,000 more E than Earth) E ~5.7x10-8 x T**4 Emax ~ 2900/T emitted emitted λ Weins Law IR Fade VIS

Absorption of Radiation by Atmosphere

Greenhouse Effect Venus to Hot(450C) 97%C02, 90x Sfc Pres of Earth , Mars to Cold (-53C)95% CO2, ~1% Sfc Pres Earth, and Earth 0.04% CO2…Just Right (15C) Recycles energy and makes the planet suitable for life as we know it. Some Trace Gases Absorb and Emit Heat (H2Ovapor,CO2,CH4,Ozone) Albedo also has important influence on Earth’s Temperature Without Greenhouse effect Earth would be about -18C Water Vapor most important Greenhouse Gas (Absorbs at different wavelengths and abundant in Atmosphere) Rough Approximation of contributions to Greenhouse effect by trace gases: -60% water vapor -20% Carbon dioxide -20% the rest to others (Ozone, Nitrous Oxide, Methane, and other species) Other Planets UCAR 2006

https://www.ucar.edu/learn/1_3_1.htm

Annual Average Energy Balance of Earth Earth Albedo ~ 30% (107W) Aprox 50% solar energy reaches earth (AK) 342 W/m2 from Earth to Space 342 W/m2 from Space to Earth In Space Solar Constant is ~1368 W/m2 (half due to night and half again due to solar zenith angle)

1 complete orbit every 365.25 days SUN- EARTH min/max 146-152 million km 1 complete orbit every 365.25 days Solar Zenith Angle Tropic of Capricorn ~23.5 deg S Tropic of Cancer ~23.5 deg N (AK)

Daylight Length Hours Daylight http://en.wikipedia.org/wiki/Twilight Earth Rotation .25 deg / min Tilt of the Earth’s axis defines length of daylight for a given latitude Hours Daylight

Net radiation = net short-wave radiation + net long-wave radiation.

https://www.ncdc.noaa.gov/cag/time-series/global/globe/land_ocean/1/8/1880-2017

"There is considerable uncertainty in future model projections "There is considerable uncertainty in future model projections. The more important message from models is that all but a few outliers predict enormous sea ice retreat this century," Oceanographer of the Navy Rear Adm. Titley July 2009 Image from Andy Armstrong/National Oceanic and Atmospheric Administration