Thursday April 19, 2012 - PowerPoint PPT Presentation

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Thursday April 19, 2012
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Thursday April 19, 2012

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  1. ThursdayApril 19, 2012 (World Distribution of Temperature; Measuring Atmospheric Pressure )

  2. The Launch Pad Thursday, 4/19/12 This weather station model shows conditions for an area of the United States. Please provide the following information for this area: wind direction wind speed sky conditions temperature dew point precipitation? barometric pressure recent change in barometric pressure

  3. Announcements • I will not be available after school today.

  4. Latest News Extreme Weather of Last Decade Part of Larger Pattern Linked to Global Warming Click below for article:

  5. World Distribution of Temperature Temperature maps help analyze temperature distribution over given areas. Temperatures are adjusted to sea level to eliminate the variable of altitude. January and July are used for analysis because they represent the temperature extremes.

  6. World Distribution of Temperature On these maps, an isotherm is a line connecting places of equal temperature.

  7. World Distribution of Temperature On a global scale, temperature patterns emerge. The temperature decreases poleward from the tropics. Isotherms exhibit a latitudinal shift with the seasons. The warmest and coldest temperatures occur over land.

  8. World Distribution of Temperature In the Southern Hemisphere, isotherms are straighter and more stable. Isotherms show the annual temperature range of ocean currents. Ranges are small near the equator, and increase with an increase in latitude Ranges are greatest over continental locations. World Mean Sea-Level Temperatures in January World Mean Sea-Level Temperatures in July

  9. Atmospheric Pressure Atmospheric pressure is the force exerted by the weight of the air above. The weight of the air above at sea level is 14.7 pounds per square inch. This pressure decreases with increasing altitude. A common measurement unit of atmospheric pressure is the millibar(mb). Standard sea level pressure is 1013.2 mb.

  10. Atmospheric Pressure Another unit used in atmospheric pressure measurement is inches of mercury. Standard sea level pressure is 29.92 inches of mercury. The instrument used for measuring atmospheric pressure is the barometer. The mercury barometer was invented by Torricelli in 1643. It uses a glass tube filled with mercury.

  11. Atmospheric Pressure Another type of barometer is the aneroid barometer, meaning “without liquid.” This type of barometer uses an expanding chamber. Another pressure instrument is the barograph, which continuously records the air pressure.

  12. Barometric Pressure Equivalents normal sea level pressure (at 0oC) = 760 mm Hg 760 mm Hg = 29.92 in. Hg = 1013.1 mb 1 in. Hg = 33.86 millibars (mb)