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Weather

Weather. Weather. Weather State of the atmosphere at a specific time and place Includes: Air Pressure (inches of Mercury or millibars) Wind (mph or knots) Temperature (Fahrenheit or Celsius) Moisture (Dew Point or Humidity). Weather. Role of the Sun

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Weather

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  1. Weather

  2. Weather Weather • State of the atmosphere at a specific time and place • Includes: • Air Pressure (inches of Mercury or millibars) • Wind (mph or knots) • Temperature (Fahrenheit or Celsius) • Moisture (Dew Point or Humidity)

  3. Weather • Role of the Sun • The heat evaporates the water into the atmosphere • This forms clouds • Which returns water to the Earth as Precipitation • Heats the air

  4. Weather • Temperature • Is measure of the movement of molecules • The higher the temperature, the faster the molecules move • The more direct radiation we receive from the sun, the warmer it feels • The more indirect radiation we receive from the sun, the cooler it is

  5. Temperature

  6. Wind • Wind • Air moving in a specific direction • As the sun heats the air: • It expands • Becomes less dense • Rises • Has Lower Atmospheric Pressure

  7. Wind • Cold Air • More Dense • Sinks • High Atmospheric Pressure • Air moves from High pressure to Low pressure • Results in wind

  8. What Causes Wind?

  9. High Pressure vs. Low Pressure

  10. Humidity Humidity • The amount of water vapor in the air • Relative Humidity • Amount of water vapor in the air compared to what it can hold at a specific temperature • Warmer air can hold more water vapor than cold air • Dew Point • The temperature at which air is saturated and condensation forms

  11. Relative Humidity

  12. Clouds Cloud Formation • Clouds form as warm air is forced upward and cools • Water vapor condenses to form tiny ice crystals • The shape and height of clouds vary with temperature, pressure and the water vapor in the atmosphere • Nimbus, clouds that are dark and full of water that sunlight can’t penetrate

  13. Rain Shadow

  14. Shape Stratus Smooth, even sheets Low Altitudes Cumulus Puffy, white clouds Flat bases common Cirrus High, thin, feathery Made of ice crystals Height Cirro High Clouds Alto Middle elevation Strato Low clouds Cloud Nomenclature

  15. Clouds Types

  16. Cirrus: Thin and Wispy

  17. Cirrostratus: Sheet Like, Transparent

  18. Altocumulus: Parallel Bands or Round Masses

  19. Nimbostratus: Dark Low Level

  20. Stratocumulus: Low Lumpy Layers

  21. Cumulus; Fair Weather Cotton Balls

  22. Cumulonimbus: Thunderstorms

  23. Weather Prediction

  24. Cloud Types

  25. Weather Patterns • Weather patterns change continuously because air and moisture move in the atmosphere • Air Mass • High and Low Pressure Weather Systems • Use a barometer to measure air pressure

  26. Air Masses • Air Mass • Large body of air with properties like the part of Earth’s surface over which it formed • Low Pressure Air Mass • Stormy weather • High Pressure • Fair weather

  27. Fronts A front is a boundary between two different air masses • Clouds and precipitation, and storms occur at the frontal boundaries • Cold Front • Colder air advances under warm air • Warm Front • Warm air advances over colder air

  28. Fronts • Occluded front • Involves three air masses of different temperatures • Stationary Front • Air masses and their boundaries stop advancing

  29. Cold Front

  30. Warm Front

  31. Occluded Front

  32. Severe Weather • Thunderstorms • Occur inside warm, moist air masses and at fronts • Warm air is forced up rapidly, where it cools and condenses • Strong updrafts of warm air and sinking, rain cooled air causes strong winds

  33. Cumulus Stage

  34. Mature

  35. Dissipating Stage

  36. Severe Weather • Lightning • Movement of air inside a storm cloud that causes parts of the cloud to become oppositely charged • Current flows between the regions of opposite electrical charge, forming a lightning bolt

  37. Severe Weather • Thunder • Lightning superheats the air, causing it to expand rapidly then contract forming sound waves

  38. Sever Weather • Tornados • A violent, whirling wind that moves in a narrow path over land • Hurricane • A large, swirling, low pressure system that forms over tropical oceans • Blizzard • A winter storm with strong winds, cold temperatures, and low visibility, that lasts more then three hours

  39. Severe Weather Safety • Watch • Means conditions are favorable • Warning • Means severe weather conditions already exist • http://www.fas.org/irp/imint/docs/rst/Sect14/Sect14_1c.html

  40. Weather Forecasts • Meteorologists • study and predict the weather • The National Weather Service makes weather maps • Station Models show weather conditions at a specific location • Isotherms are contour lines of equal temperatures • Isobars are contour lines of equal pressure • Weather fronts move east to west

  41. Station Model

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