Chapter 19 : The Atmosphere

Section 1: Characteristics of the atmosphere Atmosphere – layers of gases that surround the Earth. http://scijinks.nasa.gov/_media/en/site/atmosphere-formation/atmosphere3.jpg

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 http://www.infoplease.com/images/ESCI234ATMOSP003.gif

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

Oxygen in the atmosphere Photosynthesis – is the process where plants make oxygen from carbon dioxide in the air. http://www.exploringnature.org/graphics/ecology/oxygen_cycle_color72.jpg

Water vapor in the atmosphere http://www.exploringnature.org/db/detail.php?dbID=112&detID=2650

Ozone in the atmosphere Ozone is a form of oxygen ozone layer is in upper atmosphere which protects against UV radiation. http://www.aoas.org/images/articles/ozone_profile_cartoon.jpg

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

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.

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

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

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

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

The mesosphere Extends to an altitude of 80 km Temperature decreases as altitude increases Mesopause – temperature is -90°C (coldest in atmosphere)

The thermosphere Temperature increases steadily as altitude increases because nitrogen and oxygen atoms absorb solar radiation. Temperature has been recorded at more than 1000 °C. Lower region is called the ionsphere Where auroras take place Zone of infinite altitude - exosphere

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 http://ciese.org/curriculum/airproj/images/inversion.gif

Section 19-2 Solar energy and the atmosphere

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 http://ww2010.atmos.uiuc.edu/guides/mtr/opt/mch/gifs/sct2.gif

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.

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.

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. http://myclimatechange.net/wp-content/uploads/2012/08/GreenhouseEffect.jpg

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.

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. http://www.ux1.eiu.edu/~cxtdm/met/seasons.gif

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.

Conduction Conduction – is the transfer of heat from one substance to another by direct contact. Solid surfaces are better conductors versus air. http://earthstorm.mesonet.org/images/cond_conv_rad_small.jpg

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. http://earthstorm.mesonet.org/images/cond_conv_rad_small.jpg http://3.bp.blogspot.com/_CjKGpCbY0kU/SjuyJsIXtdI/AAAAAAAABSo/qor-9R3J8cw/s320/chap01_convection.gif

ATMOSPHERIC CIRULATION Section 19-3 ATMOSPHERIC CIRULATION

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

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.

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.

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.

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

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

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

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

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 10-15 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

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

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

http://oceanservice. noaa http://oceanservice.noaa.gov/education/pd /oceans_weather_climate/media/sea_and_la nd_breeze.swf

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