TEMPERATURE
advertisement
TEMPERATURE Temperature Data Daily Temperature • High – 90°F • Low – 60°F Daily Temperature Range? • Difference between High & Low for Day Daily Average Temperature? • Mid-point between High & Low for Day Temperature Data Monthly Temperature • Average of all Daily Temperatures in a Month Annual Temperature Annual Temperature Range? • Difference between Hottest & Coldest Month Annual Mean Temperature? • Average of all 12 Monthly Temperatures Isotherm Map Isotherm = “Equal Temperature” Line that connects same temperature Temperature Gradient Isotherm distance Close = Rapid change Wide = Gradual Change Controls of Temperature Latitude Land & Water contrast Ocean Current circulation Altitude Geographic Position Cloud Cover & Albedo Latitude Latitude most affects Temp. … Solar Radiation Annual Temp. Range… Greater in Higher Latitudes Latitude – Solar Radiation Low Sun Angles in High Latitudes… Lower Temperature Latitude – Solar Radiation High Sun Angles in Low Latitudes… Higher Temperature Land & Water Contrasts Land surface Heats & Cools Faster… to greater extremes to lesser depth Ocean Heats & Cools Slower… Ocean Circulates (Fluid) • Distributes Heat Evaporation Æ Cooling Land & Water Contrasts Differential Heating = “Specific Heat” Water absorbs more Energy without Heating Land Heats more with less Energy Land & Water Contrasts Heating Characteristics Interior Locations… • Extreme Temp. Coastal Locations… • Moderate Temp. San Diego & Dallas are same Latitude Why different Temp.? Land & Water Contrasts Same Latitude in Canada Vancouver… • Marine Winnipeg… • Continental • 5°F warmer in Summer • 36°F colder in Winter Land & Water Contrasts Northern Hemisphere… “Land” Hemisphere Greater Temp. range • More “Continental” climate Southern Hemisphere… “Water” Hemisphere Less Temp. range • More “Marine” climate Ocean Currents Atmospheric Circulation 75% of Heat Transfer Oceanic Circulation… Winds propel Currents Ocean Currents Currents & Wind transfer heat… Equalizes Latitudinal energy imbalance Wind & Ocean Currents Northern Hemisphere Clockwise Southern Hemisphere Counter-Clockwise Ocean Currents Equatorial current... Warm – Flows West Warm currents – West Cold currents – East Ocean Currents Similar Latitude in South America Rio de Janeiro… • Warm current Arica, Chile… • Cold current 10°F difference throughout year Altitude Vertical Temperature (Troposphere) Temperature Cools with Altitude Normal Lapse Rate… • –3.6°F / 1,000’ Altitude Near Equator in South America (Ecuador) Guayaquil… • Sea Level Quito… • 9,200’ 20°F difference throughout year Geographical Position Coastal Location relative to Winds… Windward coast… • Temperature moderated by ocean air Leeward coast… • Greater Temperature range… – Greater heating and cooling Windward & Leeward Coasts Same Latitude in U.S.A. Eureka, CA… • Windward Coast New York City… • Leeward Coast 34°F greater Temp. Range… • Summer & Winter Topographical Barrier Topographical Barrier (Mountains)… Windward slope… • Marine – Temperature moderated Leeward slope… • Continental – Greater Temperature range West East Topographical Barrier Same Latitude in Washington Separated by Cascade Range Seattle… • Windward side Spokane… • Leeward side 20°F Greater Temp. Range Cloud Cover & Albedo Clouds have High Albedo… Daytime… • Reflects Solar Radiation… – Cooler Air below Night… • Retains Earth Radiation… – Reduces Temp. Loss Reduces Temperature Range… Daily Temp. Cycle Monthly Temp. Cycle Cloud Cover & Albedo Daily Temperature Range… Clear… • Greater Temp. Range Overcast… • Less Temp. Range Cloud Cover & Albedo Monsoon… Cloud cover lowers summer heat Highest Temp. • Dryer month prior to rains Temperature Cycles When warmest & coldest during… Day Year Due to Net Heat Balance between… Solar Radiation Earth Radiation Lag from Peak & Low for Solar Radiation Daily Net Radiation If Solar Radiation > Earth Radiation Earth Warms up during Daytime Earth then Warms the Air Warmest Time of Day? Daily Net Radiation If Earth Radiation > Solar Radiation Earth Cools off during Nighttime Air Cools off Coolest Time of Day? Daily Temperature Cycle Warmest time of day… 2 to 5 pm Coldest time of day… Sunrise Daily Temperature Cycle Daily Temperature Cycle Influenced by Land/Water Location Inland Temp. Large Temp. Range Riverside (Oct. 9) • High = 83°F • Low = 58°F • Range = ? Coastal Temp. Small Temp. Range Santa Monica (Oct. 9) • High = 73°F • Low = 60°F • Range = ? Daily Temperature Cycle Record Daily Range in… Inland Desert Record: • 126°F in Day • 26°F at Night Annual Temperature Cycle Warmest & Coldest months differ from Summer & Winter Solstices… Warmest = July-August Coldest = January-February Lag due to Net Heat Balance between… Solar Radiation Earth Radiation Annual Temperature Cycle Influenced by Land/Water Location Inland Rapid Heating & Cooling Hottest Month? • After Summer Solstice • July Coldest Month? • After Winter Solstice • January Coastal Slower Heating & Cooling Hottest Month? • August Coldest Month? • February Annual Temperature Range Difference between… Hottest Month Coldest Month Influenced by… Latitude Proximity to Coast Annual Temperature Range Largest in… High Latitude & Inland Yakutsk, Siberia • 68°F in July • – 45°F in January • Range? = 113° Annual Temperature Range Smallest in… Low Latitude & Coastal Manaus, Brazil • 79°F in July • 82°F in January • Range? Temperature – Sea Level Map is most affected by Latitude Decreases from Equator to Poles • More extreme in Continental interiors Temperature – Sea Level January – Shifts South from Equator 90° Sun Angle at 23½°S • Northern Hemisphere – Colder inland Temperature – Sea Level July – Shifts North from Equator 90° Sun Angle at 23½°N • Northern Hemisphere – Hotter inland Annual Temperature Range Largest Range No. Hemisphere • > 110°F in Siberia Smallest Range Along Equator • < 5°F Annual Temperature Range No. Hemisphere More Land Inland extremes So. Hemisphere More Ocean Moderated Seasonal Latitudinal Shift Seasonal Migration of 60°F Isotherm Shifts most over continents • Summer Æ North • Winter Æ South Record Temperatures High = 136°F in Libya Low = –130°F in Antarctica Annual Range = 113°F in Siberia Measuring Temperature Mechanical Thermometers Temperature Change • Water Maximum Temperature • Mercury Minimum Temperature • Alcohol (Horizontal) Measuring Temperature Mechanical Thermometer Bimetal strip… • Thermograph Electrical Thermometer Thermal Resistor • Thermistor – Used in airborne Radiosondes Measuring Temperature Instrument Shelter Thermometer inside White Box… • Provides Shade • Vents • 4’ Above Ground • Over Grassy area Temperature Scales Fahrenheit Scale Freezing = 32°F Boiling = 212°F Celsius Scale – 100° between… Freezing = 0°C Boiling = 100°C Kelvin Scale Measures from “Absolute Zero” • Lowest possible Temperature • –273°C (= 0° Kelvin) Temperature Applications Degree-Days – Energy demand/consumption Heating… Below 65°F Cooling… Above 65°F Growing Crops Difference between… • Daily Mean Temperature • Base Temperature of Crop Determines Harvest date Temperature & Comfort Affects Human comfort… Sunshine Humidity… • Heat Index Wind Chill… • Feels colder during Winter Urban Heat Islands Cities… Higher Temp. than in rural areas Buildings... • Absorb heat • Heating & AC
