1. Chapter 19 : The Atmosphere

2. Section 1: Characteristics of the atmosphere
Atmosphere – layers of gases that surround the Earth.

3. Composition of the atmosphere
Nitrogen, oxygen and argon – most abundant elements
Most abundant compounds – carbon dioxide and water
Tiny solid particles – such as dust and pollen

4. Nitrogen in the atmosphere
Nitrogen makes up 78% of the atmosphere

6. Oxygen in the atmosphere
Photosynthesis – is the process where plants make oxygen from carbon dioxide in the air.

8. Water vapor in the atmosphere

10. Ozone in the atmosphere
Ozone is a form of oxygen
ozone layer is in upper atmosphere which protects against UV radiation.

11. Particles in the Atmosphere
All types of different particles – could be from combustion or wood burning as well as dust in the road.

12. Atmosphere Pressure
Gravity holds the gases of the atmosphere near the Earth’s surface
Pressure exerted on the surfaces by the atmosphere is called atmospheric pressure
As altitude increases, atmospheric pressure decreases.
Atmosphere pressure also changes as a result of differences in temperature and in the amount of water vapor in the area.

13. Measuring Atmospheric Pressure
3 types of units – atmospheres (atm), millimeters or inches of mercury and millibars (mb)
Standard atmospheric pressure – 1 atm
Sea level – 1 atm
Barometer is used by scientists to measure atmospheric pressure
Mercurial barometers
Aneroid barometers

14. Layers of the atmosphere
Distinct pattern of temperature change with increasing altitudes

15. The Troposphere
Atmospheric layer that is closest to the Earth’s surface and in which nearly all weather occurs.
Temperature decreases as altitude increases because air in this layer is heated from below.
Tropopause – temperature stops decreasing – upper boundary

16. The stratosphere
Extends from the tropopause to an altitude of nearly 50 km.
Lower region -60°C but in the upper region it is almost 0°C because of solar radiation.
0°C zone makes the stratopause – upper region of the stratosphere

17. The mesosphere Extends to an altitude of 80 km
Temperature decreases as altitude increases
Mesopause – temperature is °C (coldest in atmosphere)

18. The thermosphere
Temperature increases steadily as altitude increases because nitrogen and oxygen atoms absorb solar radiation.
Temperature has been recorded at more than °C.
Lower region is called the ionsphere
Where auroras take place
Zone of infinite altitude - exosphere

19. Temperature inversions
Main source of pollution is the burning of fossil fuels.
Temperature inversion – layering of warm air on top of cold air.
This produces smog because polluted air is trapped

20. Section 19-2 Solar energy and the atmosphere

21. Scattering
Clouds, dust, water droplets and gas molecules in the atmosphere disrupt the path of radiation from the sun.
Scattering makes the sky appear blue and the sun red at night

22. Reflection
Amount of energy absorbed or reflected depends on color, texture, composition, volume, mass, transparency, state of matter, and specific heat of the material on which solar radiation fall.
Albedo – fraction of solar energy that is reflected by a particular surface.

23. Absorption and infrared energy
Solar radiation not reflected is absorbed by the Earth’s surface.
This heats up the ground which warms up the lower atmosphere.

24. The greenhouse effect
Earth’s atmosphere reduces the escape of energy that radiates from Earth’s surface. This is similar to a greenhouse.
Some effects of the greenhouse effect are good but too much makes the Earth too hot.
Human activities are causing the average temperature of the atmosphere to increase.

25. Variations in temperature
Slight delay between absorption of energy and an increase in temperature
The temperature in any region depends on several factors, including latitude, surface features and the time of year and day.

26. Latitude and season
Latitude is the primary factor that affects the amount of solar energy that reaches any point on Earth’s surface.
Temperature varies seasonally because of the tilt of the Earth’s axis.

27. Water in the air and on the surface
The amount of water in the air affects the temperature of the region
High elevation – have less water so heat up quickly during the day and quickly cools at night
Bodies of water have more moderate temperatures
Water heats up and cools down slower than land does
Wind patterns from water are more moderate than from land.

28. Conduction
Conduction – is the transfer of heat from one substance to another by direct contact.
Solid surfaces are better conductors versus air.

29. Convection
Convection is the process by which air rises or sinks because of differences in temperature
Continuous cycle of cold air sinks and warm air rising warms the Earth’s atmosphere
Warm air is less dense so atmospheric pressure is lower
As cool air moves in it pushes up the warm air as wind.

30. ATMOSPHERIC CIRULATION
Section 19-3
ATMOSPHERIC CIRULATION

31. Atmospheric Circulation
Air normally moves from the poles to the equator
High pressure regions occur when the cold air sinks
Low pressure regions occur when hot air rises

32. The coriolis effect
Circulation of the atmosphere and oceans are affected by the rotation of the Earth on its axis.
Coriolis effect is the curving of the path of a moving object from an otherwise straight path due to the Earth’s rotation.
Objects are deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

33. Global winds
Each hemisphere contains three looping patterns of flow called convection cells
Each convection cell correlates with a wind belt. These are winds that flow in one direction.

34. Trade winds
Winds that flow toward the equator between 30° and 0° latitude
Northern Hemisphere – Northeast
Southern Hemisphere – Southeast
Called the trade winds because many trading ships traveled on these winds.

35. Westerlies
Between 30°and 60° latitude, air moving towards the poles are deflected by the Coriolis effect
Northern Hemisphere – Southwest
Southern Hemisphere – Northwest

36. Polar Easterlies 60° latitude is a low zone of pressure
They travel over the poles and when they meet with warm air from the westerlies they cause a front

37. The Doldrums and Horse Latitudes
Doldrums are where the trade winds meet (Low pressure)
Horse Latitudes – this is approximately 30° latitude

39. Wind Belts and Pressure Shifts
Wind belts do shift throughout. They will move the trade winds up and down at times.

40. Jet Streams
Narrow bands of high speed winds that blew in the upper troposphere and lower stratosphere are called jet streams
2 types
Polar jet streams - ~100 km wide and 2-3 km thick are located at altitudes of km
Polar jet streams can reach up to speeds over 400 km/h
Subtropical jet streams – warm equator air meets the colder air and the jet streams form

41. Local winds Influenced by local conditions
Winds that blow less than 50 km/h are called breezes

42. Land and Sea Breezes Land surfaces heat up quicker than sea breezes
Warm air above the land rises creating a lower pressure
A cool wind moves from water to land called a sea breeze
At night the land breezes flow from the cool land towards the warmer water

44. http://oceanservice. noaa
/oceans_weather_climate/media/sea_and_la nd_breeze.swf

45. Mountain and Valley Breezes
Valley breeze forms when warm air from the valleys move upslope.
At night cool air descends from the mountain peaks to create a mountain breeze