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Large Scale Weather

Large Scale Weather. SCI 201. Driving Questions. How does sunlight hit the Earth and how does this result in seasons? What are the various air masses on Earth and how do they form?

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Large Scale Weather

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  1. Large Scale Weather SCI 201

  2. Driving Questions • How does sunlight hit the Earth and how does this result in seasons? • What are the various air masses on Earth and how do they form? • What is the Coriolis Force and how does it affect the motion of objects in the Northern and Southern Hemispheres? • What causes the jet streams and how do they influence weather? • How are regions of high and low pressure created on the Earth and what weather is generally associated with each? • How do winds associated with areas of high and low pressure move? • What are fronts and how are they associated with precipitation?

  3. The Sun and the Earth • Seasons • Area of sunlight • Resulting air masses

  4. Air Masses

  5. Jet Stream • Interaction of the large air masses (high altitude) • Coriolis force (drawing activity - NH/SH) • Pressure above the poles and equator • More molecules above equator • Less molecules above the poles • Pressure gradient force • Cancellation and the resulting jet stream • Polar - higher winds (due to distance and T) • subtropical • In US, systems follow a general W to E pattern (*) • Usually shown P.J.S. • Cold snaps/warming trends • winter vs. summer

  6. Highs/Lows and Precipitation • High pressure in areas where air is sinking • Pushes on air below it results in higher P • Can be high/low T, but few clouds (think cloud in a bottle) • Low pressure in areas where air is rising • Opposite effect • If lots of water vapor, clouds can form, rain/snow as it rises and cools off • Rain/Snow showers and clouds around Lows

  7. Highs/Lows and Winds • At high altitudes • In a circle to the left around lows • In a circle to the right around highs • Nearer the Earth’s surface • Spiral inward around lows • Spiral outward around highs • Blowing winds suggest a change from a high to low pressure area

  8. So far… • High and low P areas move across the Earth • They take winds that circulate around those areas with them • Large scale, cover large portions of the US • Within and between are smaller regions of cold air, warm air, dry air, humid air, and combos

  9. Fronts • Pan demo • Small scale areas come into contact • Cold front - cold air overtakes warm air • Warm front - warm air overtakes cold air • Stationary front - neither displaces the other

  10. storms • Depends on DT between cold and warm air and humidity of cold and warm air • If warm air is humid - clouds and possibly rain and snow • When cold air overtakes warm air, warm air rises rapidly and cools rapidly, big thunderstorms and snowfalls • When warm air overtakes cold air, the rising is more gradual, leads to steady, longlasting precipitation

  11. Driving Questions • How does sunlight hit the Earth and how does this result in seasons? • What are the various air masses on Earth and how do they form? • What is the Coriolis Force and how does it affect the motion of objects in the Northern and Southern Hemispheres? • What causes the jet streams and how do they influence weather? • How are regions of high and low pressure created on the Earth and what weather is generally associated with each? • How do winds associated with areas of high and low pressure move? • What are fronts and how are they associated with precipitation?

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