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Weather

Weather. A study in Variables. What is meteorology?. Meteorology is the study of current atmospheric conditions. Very simplified definition! Includes the sciences of chemistry & physics. Can include climatology, ecology, & oceanography.

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Weather

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  1. Weather A study in Variables

  2. What is meteorology? • Meteorology is the study of current atmospheric conditions. • Very simplified definition! • Includes the sciences of chemistry & physics. • Can include climatology, ecology, & oceanography. • Goals include understanding, predicting, and artificial control of phenomena of the atmosphere.

  3. Why isn’t the meteorologist always right? • Weather consists of MANY related variables. These include: • Air pressure • Atmosphere structure • Water and water vapor • Energy and heat (a.k.a. temperature) • Wind and air currents • Global rotation and effects on wind

  4. Weather Forecasting = 4 pieces • Observations • Data collection • Radar • Satellites • Weather stations • Computer Models • Many! • Up to the meteorologist to choose • Farther out in time = less reliable. • Audience interpretation

  5. What makes weather happen? • Variables! They all interact to make the weather, and they are all related. • We will look at the role each variable plays in creating our weather. • Different variable each week. • This week focus on atmosphere, energy/heat.

  6. Weather information • Weather information focus will be in form of maps • Information on the map is generated from weather stations. • Weather stations report on their local conditions. • This information is compiled into the weather map. • Large group focus will be on each variable (information represented by stations), small groups will be supporting labs and activities.

  7. Weather Stations • Report on local conditions • Almost completely automated • Observe: Temperature, humidity, air pressure, wind speed and direction, cloud cover and height, visibility and weather (rain, snow, fog)

  8. Variable: Atmosphere - composition • 78% Nitrogen • 21% Oxygen • .93% Argon • Remainder are trace gases, dust, pollution. • .039% Carbon dioxide (major greenhouse gas) • Water varies with temperature, also important for storing and releasing heat energy (latent heat). • Dust and pollutants vary with location.

  9. Variable: Atmosphere - Structure • Consists of four major layers (top to bottom) • Thermosphere • Mesosphere • Stratosphere • Troposphere • Mnemonic: Too Many Stupid Tests • Separated by a “-pause” • Tropopause, stratopause, mesopause • Space is the “exosphere”, transition = “ionosphere”

  10. Atmosphere structure (pg 480)

  11. Troposphere • 0-10 Km (Mt. Everest peak is above the troposphere) • Temperature decreases with height. • Earth radiates heat so air is warmer closer to the ground. (mountains) • Pressure decreases with height.(airplanes) • Layer of the atmosphere we live in. • Top boundary is the tropopause. • Jet stream located here. • Lid of the weather.

  12. Stratosphere • 10-50 Km • Pressure decreases with height. • Air temperature increases with height. • Ozone layer located here. • Absorbs UV causing the rise in temperature. • Commercial airplanes fly here (bottom). • Supersonic airplanes fly here (top). • Top boundary is the stratopause.

  13. Mesosphere • Pressure decreases with height. • Pressure is so low that blood would boil at normal body temperatures. • Temperature decreases with height. • Little/No ozone to absorb UV • 50-85 Km • Visible meteors (shooting stars) occur here. (friction) • Top boundary is the mesopause.

  14. Thermosphere • Pressure decreases with height. • Temperature increases with height. • Few molecules present • If energy is absorbed, it will result in a large temperature increase. • Molecules moving FAST. • Aurora borealis located here and beyond. • Lights due to solar winds interacting with Earth’s magnetic field.

  15. Variable: Heat Energy • Heat is a measure of how much molecules are moving. • Three main forms of heat energy transfer in the atmosphere. • Conduction- molecules crash together to transfer heat energy. • Convection- the transfer of heat by mixing or circulation. • Radiation- the transfer of energy by electromagnetic waves (EM). • Heat flow ALWAYS from high to low temperature matter

  16. Conduction-molecules touching • Substances conduct heat differently – metal is a good conductor • Air is very poor conductor • For atmosphere – conduction not so important

  17. Convection - molecules mixing • Lots of heat transferred in atmosphere by convection • Happens in fluids like the ocean and air where atoms and molecules are free to move • Hot stuff rises, cold stuff sinks.

  18. Radiation - EM waves • Does not need molecules in order to transfer heat like convection and conduction. • Can travel through outer space. • All objects emit radiant energy. (Night vision goggles/cameras) • Hotter objects emit more energy (shorter wavelengths) than cooler objects. • Objects that are good absorbers are also good emitters.

  19. So What? • Earth gets ALL of its incoming energy by radiation from the sun. • 30% of incoming solar radiation is reflected and scattered. (Does nothing for Earth.) • (20% reflected from clouds, 5% reflected from sea/ice/sand, 5% reflected from atmosphere.) • 20% of incoming solar radiation is absorbed by the atmosphere and clouds. • 50% of incoming solar radiation is absorbed at the surface.

  20. Incoming radiation (pg 486)

  21. Effects on the atmosphere. • The atmosphere gains energy from the sun. • The Earth gains energy from the sun and Earth also radiates heat into the atmosphere. • The greenhouse gases (water & CO2) in the atmosphere trap the heat radiated by the Earth. • So, the atmosphere is a sandwich!

  22. Sun Atmosphere Earth The atmosphere is a sandwich? • Heated from above by the sun. • Heated from below by the Earth. • Atmosphere is the hamburger, and the heat sources are the buns!

  23. The REAL sandwich (not in book)

  24. Earth is heated unevenly • Land and water heat differently. • Water has a high specific heat (amount of energy needed to raise temperature). • It acts like an energy sponge. It will soak up or release energy without changing temperature(latent/hidden heat). • Water won’t heat or cool as fast as land. • Water won’t reach the temperature extremes that land will. • Land close to large bodies of water will be more moderate. • Higher elevations are cooler. • Global location/latitude makes a difference.

  25. Earth Temperature Distribution

  26. Uneven heating has effects. • Causes differences in pressure and winds that we will discuss in the coming weeks.

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