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8/27/18

Heat (Q) Change

• 1 calorie = 4.18 ΔQ = m cwater ΔT • : Total Kinetic • Q in • Temperature: Average • cwater = 4186 J/kg°C • m = . Per unit : m/vol = density of the • Heat that causes a change in temperature: • ΔQ = ρ cwater ΔT • vol

Heat Capacity Substance Sp. Heat (cal per gm per °C) Water 1.000 •The heat absorbed or released in .48 the change of of water. Wood .42 •Latent heat of fusion = 80cal/gm Brick .21 •Latent heat of = 540 Sand .20 cal/gm Air .17 •The 1 gm ice cube is 0°C. Copper .09 •What happens if it absorbs 5 cal of Gold .03 heat?

Latent Heat Latent heat

Latent Heat

Latent Heat

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Heat Heat Fluxes Transfer of heat in/out of the ocean Transfer of heat in/out of the ocean surface • = Quantity/(Area • Time) • Heat In - One Heat Flux • Heat Flux = Joule /(m2•s) – Shortwave Radiation or Insolation (Qs) • Heat Out - Three Heat Fluxes – Longwave or Back Radiation (Qb) • 1 Watt = 1 Joule/s These are the 2 heat fluxes involving • Heat Flux = W/m2 Radiation

Heat Fluxes Heat In = Heat Out Transfer of heat in/out of the ocean surface is not true for the short-term

• Shortwave Radiation or Insolation (Qs) • Longwave or Back Radiation (Qb) • Latent Heat Flux (Qe) • Sensible Heat Flux (Qh)

Heat In = Heat Out

Smaller Region of Ocean Advective Heat Flux

• Sept: Measurements show Qs = Qb + • Qv Qe +Qh. What happens to the Bay’s temperature? • Qv is the only heat flux that • June: Measurements show Qs > Qb + does not transfer heat in and Qe +Qh. What happens to the Bay’s out of the ocean (through the temperature? surface) • June: Measurements show the Bay’s temperature was constant. How?? • Qv transfers heat in and out of a region

2 8/27/18

Heat Fluxes Qs - Qb - Qe - Qh

20 200 180

Bay

+/- = 0

Unequal Surface Heating/Cooling Heating by Latitude Cooling Produces: Annual Average • Wind Driven Circulation (surface currents) – Pump heat poleward • Thermohaline Circulation (deep currents) – Pump cold water equatorward

• Oceans circulate to redistribute heat, caused by the unequal heating/cooling at the surface.

Stefan-Boltzmann Law

Q (W/m2) = cT4(°K) C =5.67 x 10 -8 W/m2 °K4 EM Spectrum

3 8/27/18

Wien’s Law Energy Spectra 2897.8µm λ(µm) = T(! K)

• What gives off longer wavelength energy, the Earth (10°C) or the Sun (6000°C)?

Shortwave Budget Shortwave Radiation Albedo + + Transmissivity = 100% Albedo • Once the Sun’s radiation reaches Earth: • A certain % is reflected away • A certain % is absorbed in the atmosphere and is converted to heat Qs • The remainder is absorbed by the land/ ocean (Qs) Absorptivity

Transmissivity

Annual Global Average Annual Qs in W/m2

Radiative Budget

4 8/27/18

Latent Heat Latent Heat Flux (W/m2)

• Qe = E • L • ρ – E - evaporation rate – L - latent heat of evaporation (540 cal/gm) – ρ - density

• Qe = ce (qs - qa)W -3 – ce = 1.5 x 10 – qs = saturation (mb) – qa = actual vapor pressure (mb) – W = wind speed (m/s)

Sat. Vapor Pressure Vapor Pressure When = 90% is (qs - qa) a • Vapor Pressure - the air pressure produced by all large or small value? the in the air (a portion of the total air pressure). It is a measure of how much water is in . Saturation the air. Unit is millibar. • Saturation Vapor Pressure - the maximum amount (qs) of water vapor that can be in the air (i.e. when humidity is 100%). Its value depends on the air temperature Unsaturated • Actual Vapor Pressure - the actual amount of . water vapor in the air

Qe and Temperature Qe = c(qs - qa)W • Late at night the temperature in Conway • When (q - q ) is small, air is close to s a suddenly plummets. What happens to the saturation, humidity is high, evaporation is latent heat flux? Why? small • T down, qs – qa down, humidity up, Qe down

• When (qs - qa) is large, air is dry, humidity is low, easy to evaporate • The latent heat flux IS dependent on temperature, although temperature is not in the equation. • (qs - qa) is the opposite of humidity

5 8/27/18

Temp and Humidity

(Global Annual Averages) For every 100 that reach Earth: 22 units leave the oceans as Qe Latent Heat Flux Radiative Budget

22

Sensible Heat Flux Sensible Heat Flux (conduction/)

• Qh = ch (Ts - Ta)W -3 – ch = 1.2 x 10 – Ts = sea temperature

– Ta = air temperature – W = wind speed – When Ts > Ta, the sensible heat flux represents cooling

• Bowen’s Ratio B = Qh/Qe

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For every 100 units of Energy

(Global Annual Averages) that reach Earth: For every 100 units of Energy that (Global Annual Averages) reach Earth: 7 units leave the oceans as Qh • 22 units leave the oceans as Qe Radiative Budget • 7 units leave the oceans as Qh (smallest of the 3 cooling terms) 22 7 • These fluxes do not transfer energy in/out of Earth system, but transfer energy from the oceans to the atmosphere.

Radiative Budget Calculating Back Radiation (Qb)

2 4 • Radiation leaving ocean (W/m )= csb T(°K) • °K = °C + 273 • Need to know the % that returns to Earth (or escapes & becomes heat) to estimate Qb • Qb = Radiation leaving ocean - radiation returned to ocean

Global Heat Budget Global Heat Budget

• Animation • Heat In = Heat Out » Qs = Qe + Qb + Qh • On average: Qs= (44%)Qe + (42%)Qb + (14%)Qh • (W/m2)

• Heat In = Heat Out Qs = Qe + Qb + Qh • On average: Qs= (44%)Qe + (42%)Qb + (14%)Qh • (W/m2)

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