ATM OCN 100 Summer ATM OCN Summer 2000 LECTURE 5 AIR TEMPERATURE: A Fundamental Weather Element u A. BACKGROUND u B. THERMOMETRY u C. CLIMATOLOGY of NEAR-SURFACE AIR TEMPERATURE

ATM OCN 100 Summer C. THE CLIMATOLOGY of NEAR- SURFACE AIR TEMPERATURE (con’t.) u Average Daily Temperatures & Degree-Day Units – Background – Types of Degree-Day Units F Heating Degree-Day Units F Cooling Degree-Day Units F Growing Degree-Day Units – Degree-Day Units Computations (where...)

ATM OCN 100 Summer DEGREE-DAY CALCULATIONS u Calculate daily average temperature & then Heating Degree-Day Units:

ATM OCN 100 Summer HEATING DEGREE-DAY CALCULATION u If T max = 40 o F and T min = 30 o F, then:

ATM OCN 100 Summer DEGREE-DAY CALCULATIONS u Calculate daily average temperature & then Cooling Degree-Day Units:

ATM OCN 100 Summer COOLING DEGREE-DAY CALCULATION u If T max = 80 o F and T min = 60 o F, then:

ATM OCN 100 Summer D. VARIATION OF OBSERVED AIR TEMPERATURE WITH HEIGHT u Temperature lapse rates – Rate of cooling with height – Units: degrees per meter or feet or kilometers u Layer nomenclature – lapse – inversion – isothermal where... where...

ATM OCN 100 Summer LAPSE CONDITIONS LAPSE CONDITIONS Temperature decreases with height

ATM OCN 100 Summer INVERSION CONDITIONS INVERSION CONDITIONS Temperature increases with height

ATM OCN 100 Summer ISOTHERMAL CONDITIONS ISOTHERMAL CONDITIONS Temperature remains constant with height

ATM OCN 100 Summer VERTICAL TEMPERATURE VARIATIONS VERTICAL TEMPERATURE VARIATIONS (con’t) u The Standard Reference Atmosphere u The Temperature Spheres – Troposphere – Stratosphere – Mesosphere – Thermosphere u The boundaries or “pauses”

ATM OCN 100 Summer U.S. STANDARD ATMOSPHERE

ATM OCN 100 Summer VERTICAL TEMPERATURE VARIATIONS VERTICAL TEMPERATURE VARIATIONS (con’t) u The Standard Reference Atmosphere – The Temperature “Spheres” – The boundaries or “pauses” u Reasons for vertical temperature structure u Implications of vertical temperature structure

ATM OCN 100 Summer RADIOSONDE LOCATIONS

ATM OCN 100 Summer

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18 ATM OCN Summer 2000 LECTURE 4A ATMOSPHERIC ENERGETICS: HEAT, ENERGY & ENERGY TRANSPORT u A. INTRODUCTION –What maintains the operation of our planetary system?

ATM OCN 100 Summer B. ENERGY & POWER u Definitions –Energy: Ability of a system to do work. –Power: Time rate of energy production or consumption. u Importance

ATM OCN 100 Summer B. ENERGY & POWER (con’t.) u Types of Energy (In the Atmosphere) –Kinetic –Potential –Radiant –Internal or “heat” energy –Chemical –Physical phase Transformation –Electrical

ATM OCN 100 Summer B. ENERGY & POWER (con’t.) u Energy Units –British Thermal Units (BTU) –Calories –Joules u Power Units –Watts

ATM OCN 100 Summer C. ENERGY EXCHANGE PROCESSES u Conservation of energy –Energy cannot be created or destroyed; –Energy can change forms; –Energy can be transported; –Specification by Thermodynamics Laws. u Energy transport Requirements –From high energy (hot) to low energy (cold).

ATM OCN 100 Summer C. ENERGY EXCHANGE PROCESSES (con’t.) u Types of energy exchange or transport modes –Conduction –Convection –Radiation where...

ATM OCN 100 Summer ENERGY TRANSPORT: CONDUCTION u Energy transfer by molecular vibrational motion.  Requires molecular contact: Transport medium is typically a solid. u In general: –Metals are good heat energy conductors; –Air is a poor heat conductor.

ATM OCN 100 Summer ENERGY TRANSPORT: CONVECTION u Energy Transport by molecular motion through bulk transport.  Requires movement of medium: Transport medium is a fluid only. u In general: –Fluid density differences drive convection; –Convection works well in air & water.

ATM OCN 100 Summer ENERGY TRANSPORT: RADIATION u Energy Transport is by radiating disturbances in electrical & magnetic fields.  Does not requires a medium: Transport most efficient in vacuum. u Radiation is important for maintenance of planetary climate.

ATM OCN 100 Summer D. HEAT (or HEAT ENERGY) u Definition –A form of energy; –Proportional to total amount of thermal energy found in object. u Important considerations –Heat Flow F Requires a temperature difference; F Flow from hot to cold. –Sensible heat Vs. Latent heat where...

ATM OCN 100 Summer D. HEAT ENERGY (con’t.) u Sensible heat –“Feelable Heat” –Measurement of heat & thermal energy: –Change in heat = constant x temperature change u Latent heat –“Hidden Heat” –Involves Physical Phase Transformation; –No temperature change.

ATM OCN 100 Summer E. A PRACTICAL EXAMPLE u WIND-CHILL & WIND-CHILL EQUIVALENT TEMPERATURE –What do these terms mean? –Human significance.

ATM OCN 100 Summer BACKGROUND WIND-CHILL & WIND CHILL EQUIV. TEMP. BACKGROUND u HEAT LOSS FROM HUMANS –Radiation; –Convective Heat Loss; –Latent Heat Loss. u CONVECTIVE HEAT LOSS depends upon: –Difference between skin & air temperature; –Wind speed.

ATM OCN 100 Summer THE DEFINITIONS u WIND-CHILL –A form of heat energy loss; –Proportional to: F air temperature & F wind speed. –Units: kcal/square meter/hour

ATM OCN 100 Summer THE DEFINITIONS (con’t.) u WIND-CHILL EQUIVALENT TEMPERATURE –A temperature-based index; –Air temperature for calm conditions that produces same convective heat loss as actual combination of ambient air temperature & wind speed; –Units degrees Fahrenheit (or Celsius).

ATM OCN 100 Summer

34 HUMAN COMFORT & SAFETY: Cold Stress u FROST BITE u HYPOTHERMIA