Atmosphere

1. Atmosphere Chapter 23

2. Meteorology • Study of the atmosphere. • Meteorologists are scientists who study all the characteristics of the atmosphere. • They also study weather and climate.

3. Weather • Is the general condition of the atmosphere at a particular time and place. • Includes temperature, air movements, and moisture content.

4. Climate • General weather conditions over many years.

5. Meteorology • Meteorologists apply their forecasting skills to special fields such as agriculture, aviation, forestry, or health.

6. Composition of the Atmosphere • Air is a mixture of chemical elements and compounds. • Most abundant elements in the air are gases: nitrogen, oxygen, and argon. • Most abundant compounds are gases: carbon dioxide and water vapor.

7. Water vapor • Added to air by evaporation. • Most evaporation comes from the oceans, but also includes ponds, lakes, streams, and the soil. • Plants give off water vapor during transpiration. • It is removed during evaporation: condensations and precipitation.

8. ozone • Another important substance in the upper atmosphere in a form of oxygen. • Protects the earth from harmful ultraviolet rays of the sun. • Human activities have harmed the ozone layer: CFCs-chlorofluorocarbons such as from refrigerators and air conditioners.

9. Atmospheric Dust • Atmosphere contains various kinds of tiny solid particles. • Includes mineral particles lifted from fields by winds. • Volcanic dust and microscopic organisms.

10. Oxygen in the Atmosphere • Amount is the result of natural process. • Animals, bacteria, & plants remove oxygen from the air as part of their life processes. • Forest fires, burning of fuels, & weathering of some rocks also use up oxygen. • Produce during photosynthesis.

11. Nitrogen in the Atmosphere • Amount of nitrogen in the atmosphere is maintained through the nitrogen cycle. • Nitrogen moves from the air to the soil, to plants & animals, & back again to the air. • Nitrogen is removed from the air mainly by the action of nitrogen-fixing bacteria.

12. Nitrogen fixation • Microscopic organisms live in the soil & on the roots of certain plants. These bacteria convert the nitrogen to a form that plants can use. • Ammonia nitrate

13. Atmospheric Pressure • Gravity pulls the gases of the atmosphere toward the earth’s surface & holds them there. • Due to gravity, 99% of the total mass of the atmospheric gases is found with in 32 km of the earth’s surface.

14. Atmospheric Pressure • Ration of the force of the air to the area of the surface on which it presses. • If you have been in an airplane or high in the mountains, you have felt the effect of sensation on your ears. A popping sensation or your ears filling up with air.

15. Mercurial Barometer • An instrument that measures pressure. • Atmospheric pressure presses on the liquid mercury in a well at the base of the barometer. • A reading of 760 mm of mercury indicates standard atmospheric pressure, or 1 atmosphere. • Weather maps use millibars (mb). 1 mb is equal to 0.001 of standard atmospheric pressure.

16. Types of Barometers • Aneroid barometer is a type of barometer that does not contain mercury. Aneroid means “without liquid”. • Altimeter can also measure altitude above sea level.

17. Layers of the Atmosphere • 4 layers are: troposphere, stratosphere, mesosphere, and thermosphere.

18. Troposphere • Atmospheric layer closest to the earth’s surface. • In Greek it means, “change”. • Almost all the water vapor & carbon dioxide in the atmosphere is found here. • Tropopause-temperature remains nearly constant.

19. Stratosphere • Layer of the atmosphere that extends upward from the tropopause to an altitude of 50 km. • Stratosphere is the high-temperature zone, that marks the upper boundary.

20. Mesosphere • Above the stratopause & extending to an altitude of about 80 km is this atmospheric layer. • Mesopause is the upper boundary that is marked by a return to increasing temperatures.

21. Thermosphere • Atmospheric layer above the mesopause. • Temperature increases steadily with altitude. • Thermometer cannot accurately measure the temperature here because the air is thin.

22. Thermosphere continued • Ionosphere is the lower region of the thermosphere, at an altitude of 80 km to 550 km. • Exosphere os the zone of indefinite altitude. It extends for thousands of kilometers above the earth.

23. Air Pollution • Any substance that is harmful to people, animals, plants, or property. • Substances found in air that are pollutants: sulfur dioxide, carbon monoxide, lead, & hydrocarbons. • Mains source is the burning of fossil fuels.

24. Air Pollution continued • Acid precipitation is another harmful side effect of the burning of fossil fuels. • Air pollution can become a more serious problem as result of certain weather conditions. • Temperature inversion is when a layering of warm air on top of cool air. • Controlled by preventing air pollutants.

25. Section Review 23.1 • 1. What are the two most abundant elements in dry air at sea level? • 2. What does a barometer measure? • 3. In which layer of the atmosphere do weather changes occur?

26. Answers • 1. Nitrogen & oxygen • 2. atmospheric pressure • 3. the troposphere

27. 23.2 Solar Energy & the Atmosphere • Earth’s atmosphere is heated in several ways by the transfer of energy from the sun.

28. Radiation • All of the energy that the earth receives from the sun travels through space between the earth & the sun. • Includes all forms of energy that travels through space as waves. • Cannot see the forms called X-rays & radio waves.

29. Radiation continued • Travels through space in the form of waves at high speed. • Wavelength is the distance from one wave crest. • Various types of radiation differ in the length of their waves. • Visible light consists of waves you see in different colors.

30. Radiation continued • Wavelengths shorter than visible include ultraviolet rays, z-rays, & gamma rays. • Longer wavelengths include infrared waves & radio waves. • Electromagnetic waves make up all forms of radiation.

31. Radiation continued • Electromagnetic spectrum is a complete range of wavelengths. • Most energy reaching the earth from the sun is in the form of electromagnetic waves.

32. Skin Cancer • The amount of ultraviolet radiation that does reach the earth’s surface causes sunburn on skin that is exposed to direct sunlight too long.

33. Scattering • Clouds, dust, and gas molecules in the atmosphere affect the path of radiation from the sun. • Means that water droplets and dust suspended in the atmosphere reflect and bend the rays.

34. Reflection • 20 % of solar energy is absorbed by atmosphere. • 30 % is scattered back into space or is reflected from clouds or earth’s surface. • 50 % is absorbed by the surface. • Chart on page 465 shows reflection and absorption by different surfaces.

35. Albedo • The fraction of solar radiation reflected by a particular surface is albedo. • Albedo of the moon is .07 %. • What percent of the total solar energy reaching the moon is reflected?

36. Absorption & Infrared Energy • The warmth of the sun you feel is infrared rays. • Infrared rays produced by materials on the earth’s surface is mostly absorbed by water vapor and carbon dioxide.

37. Greenhouse Effect • Process by which the atmosphere traps infrared rays over the earth’s surface. • Increased carbon dioxide levels have caused the earth to be a warmer planet. • Global warmin

38. Variations in Temperature • Factors causing changes in temperature are: • Latitude • Elevation

39. Conduction and Convection • Conduction is when molecules in a substance move faster as they are heated. • Type of energy transfer in which vibrating molecules pass heat along to other vibrating molecules by direct contact. • Convection is the energy transfer of heat through the movement of heated material.

40. Section 23.2 Review • 1. What type of solar radiation causes sunburn? Answer: ultrviolet

41. 2. Why is the atmospheric pressure lower beneath a mass of warm air than beneath a mass of cold air? Answer: Because warm air is less dense than cold air and thus presses down on the earth with less force than an equal volume of cold air.

42. 23.3 Winds • Because the earth receives more solar energy at the equator than at the poles, there is a belt of low air pressure at the equator.

43. Global Winds • Circulation of the atmosphere as well as the oceans is affected at the rotation of the earth on its axis. • Rotation of the earth causes surface winds in the Northern Hemisphere to deflect to the right and those in the Southern Hemisphere to the left. This motion is called the Coriolis effect.

44. Convection Cells • This is the air flowing from the equator completes three looping patterns of flow. • Northern and Southern Hemispheres each have three convection cells.

45. Trade Winds • Winds in both hemispheres flowing toward the equator between 30 degrees and 0 degrees latitude. • Trade winds flowing from the northeast are called northeast trades. • Trade winds in the Southern Hemisphere are called southern trades.

46. Doldrums • This is a trade wind system of the Northern and Southern Hemispheres meet at the equator in this narrow zone.

47. Horse latitudes • This is the subtropical high-pressure belt. • The surface winds here are weak and changeable. The name horse latitudes was given to this region.

48. Westerlies • Flow of winds in both Northern and Southern Hemispheres. • Northern Hemisphere, the westerlies are southwest winds. • Southern Hemisphere, the westerlies are northwest winds. • Located in the belt between the 40 degree & 60 degree latitude.

49. Polar Easterlies • Third wind belt near the poles. • Poleward of the belt of westerlies, at about 60 degree latitude, is a belt of low pressure. • Subpolar lows result from warm air moving poleward from subtropical high is lifted by cold polar air moving toward the equator.

50. Polar easterlies • Surface winds created by the polar high pressure are deflected by the Coriolis effect. • Strongest coming off the Antarctica.