Unit 1 Topic # 3 Atmosphere

The atmosphere formed over 4 billion years ago Volcanic eruptions released gases into the developing atmosphere Gases released water vapor, carbon monoxide, carbon dioxide, hydrochloric acid, methane, Meteoritic bombardments have shaped it as well

Water vapor in the atmosphere condensed and rain down forming lakes and oceans Earliest organisms in the ocean released oxygen in the atmosphere Modern Atmosphere: 71 % Nitrogen 28 % Oxygen 1% water vapor, argon, carbon dioxide Trace gases like ozone

Divide your notes into the layers of the atmosphere

The sun’s radiation spans the infrared, visible, and ultraviolet light regions 4 distinct layers the troposphere, stratosphere, mesosphere, and thermosphere Troposphere= 8-16 kilometers, Thickness of layer varies depending on location and seasons. Contains largest percentage of the mass of the layers

Temperature is warm due to absorption of infrared radiation from the surface by water vapor and greenhouse gases “Region of mixing”= mixing of materials called convection (Hot air rises, cold air falls) All weather phenomena occur here

Stratosphere temperatures are constant Ozone (O3) in the atmosphere is mostly found here Ozone absorbs solar energy (Ultraviolet radiation) causing temperatures to rise Helps to protect by absorbing most of the harmful UV radiation from the sun

Stratosphere Little Convective mixing of gases Mesosphere= Thinnest layer and becomes increasingly dominated with lighter gases Thermosphere= Blocks harmful X-ray and UV radiation from reaching our planet Contains charged gas molecules that when hit by solar energy begin to glow and produce light

This reaction with magnetic forces cause the Northern Lights (Aurora borealis)

CLIMATE: A BRIEF INTRODUCTION Weather is a local area’s short-term physical conditions such as temperature and precipitation. Climate is a region’s average weather conditions over a long time. Latitude and elevation help determine climate.

Earth’s Current Climate Zones Figure 5-2

Solar Energy and Global Air Circulation: Distributing Heat Global air circulation is affected by the uneven heating of the earth’s surface by solar energy, seasonal changes in temperature and precipitation. Figure 5-3

The region near the equator receives direct sunlight Higher latitudes hit at an angle and is scattered and spread out over a larger area Some areas reflect more solar energy than others Albedo= The percentage of incoming sunlight reflected from a surface

Earth’s Tilt Causes Seasonal Changes Earth’s axis of rotation is tilted 23.5 degrees Earth’s orbit around the sun causes most regions of the world to experience seasonal changes in temperature and precipitation

Wind Convecting air masses in the troposphere create air currents known as winds Air movement begins in the equatorial region because it receives more solar radiation Rotation of the earth causes air masses moving to the north to be deflected to the right and air masses to moving south to be deflected to the left. This is known as

Coriolis Effect Global air circulation is affected by the rotation of the earth on its axis. Figure 5-4

Convection Currents Global air circulation is affected by the properties of air water, and land. Figure 5-5

Heat released radiates to space Moist surface warmed by sun LOW PRESSURE HIGH PRESSURE Heat released radiates to space Condensation and precipitation Cool, dry air Falls, is compressed, warms Rises, expands, cools Warm, dry air Hot, wet air Figure 5.5 Natural capital: transfer of energy by convection in the troposphere. Convection occurs when hot and wet warm air rises, cools, and releases moisture as precipitation and heat (right side). Then the more dense cool and dry air sinks, gets warmer, and picks up moisture as it flows across the earth’s surface to begin the cycle again. Flows toward low pressure, picks up moisture and heat HIGH PRESSURE Moist surface warmed by sun LOW PRESSURE Fig. 5-5, p. 103

Convection Cells Heat and moisture are distributed over the earth’s surface by vertical currents, which form six giant convection cells at different latitudes. Figure 5-6

Atmospheric Conditions El Nino is a period of ocean warming in the eastern tropical Pacific Ocean Neutral Conditions: West Pacific Warm ocean water Low pressure Unstable atmospheric conditions East Pacific Cold water upwelling High pressure Stable atmospheric conditions

El Nino Tradewinds slow and reverse direction Eastern Pacific Upwelling ceases Warmer surface water STHP weakens Wet and unstable conditions Western Pacific Cooler surface water Low pressure weakens Drier and stable conditions

El Nino causes heavy rainfall and mudslides in California & South American Coast Coastal erosion in California Drought & fire in Western Pacific Loss of cold water upwelling and diminished phytoplankton blooms in E. Pacific Collapse of fisheries due to loss of cold water upwelling Increased rainfall and vegetation in dry arid places

Ocean Currents: Distributing Heat and Nutrients Ocean currents influence climate by distributing heat from place to place and mixing and distributing nutrients. Figure 5-7

(b) The earth's surface absorbs much of the incoming solar radiation (a) Rays of sunlight penetrate the lower atmosphere and warm the earth's surface. (b) The earth's surface absorbs much of the incoming solar radiation and degrades it to longer-wavelength infrared (IR) radiation, which rises into the lower atmosphere. Some of this IR radiation escapes into space as heat, and some is absorbed by molecules of greenhouse gases and emitted as even longer-wavelength IR radiation, which warms the lower atmosphere. (c) As concentrations of greenhouse gases rise, their molecules absorb and emit more infrared radiation, which adds more heat to the lower atmosphere. Figure 5.7 Natural capital: the natural greenhouse effect. When concentrations of greenhouse gases in the atmosphere rise, the average temperature of the troposphere rises. (Modified by permission from Cecie Starr, Biology: Concepts and Applications, 4th ed., Pacific Grove, Calif.: Brooks/Cole, 2000) Fig. 5-7, p. 104

Ocean Currents: Distributing Heat and Nutrients Global warming: Considerable scientific evidence and climate models indicate that large inputs of greenhouse gases from anthropogenic activities into the troposphere can enhance the natural greenhouse effect and change the earth’s climate in your lifetime.

Topography and Local Climate: Land Matters Interactions between land and oceans and disruptions of airflows by mountains and cities affect local climates. Figure 5-8

Hurricanes form over tropical oceans where 2 opposing winds meet and begin to swirl Low Pressure area develops in the middle of swirl & begins to rotate counterclockwise Hurricanes need warm water to provide energy for the storm

A Hurricane brings Strong winds that spiral counterclockwise Heavy precipitation Storm surges (water piles up by storm and then winds blow water inland) Storms typically travel across an area of warm moist air that runs near the equator Storm gets strength from warm water

BIOMES: CLIMATE AND LIFE ON LAND Different climates lead to different communities of organisms, especially vegetation. Biomes – large terrestrial regions characterized by similar climate, soil, plants, and animals. Each biome contains many ecosystems whose communities have adapted to differences in climate, soil, and other environmental factors.