Chapter 2 - The Atmosphere

Nitrogen - 78% * Fundamental for living organisms. Deposits through nitrogen fixation and reaction involving lightning and subsequent precipitins.
Oxygen - 21% * Produced through photosynthesis
Water Vapor - 0-4% * Large amounts near the equator, areas with low atmospheric water vapor are over deserts and polar areas.
Carbon Dioxide - <<1% * Produced during cellular respiration, combustion of fossil fuels, and decay of organic matter. Required for photosynthesis.
Methane - <<<1% * Contributes to the greenhouse effect.
Nitrous Oxide - <<<1% * Contributor to the greenhouse effect. Single most important contributing substance reducing stratospheric ozone.
Ozone - <<<1%’ * Most found in the stratosphere. Absorbs UV Radiation.

The atmosphere is split up into multiple layers.
Troposphere * Weather occurs in this zone. * 75% of atmospheric mass is in this zone.
Stratosphere * Temperature increases because of the UV radiation in this zone.
Mesosphere * Coldest layer. * Ice Clouds occur here.
Thermosphere * Molecules are converted into ions. * Gamma Rays, X-Rays, UV radiation make the temperature rise.

Weather * Caused by the movement or transfer of heat which causes unequal heating of the earth’s surface.
Climate * Describes the total of all weather occurring over a period of years.
Radiation * The flow of electromagnetic radiation. It is how the Earth receives solar energy.
Conduction * Transfer of heat through solid substances. * Causes a difference in temperature between different parts of the substance.
Convection * The movement of warmer molecules in the air. * Primary way energy is transferred from hotter to colder regions in the Earth’s atmosphere. Determines weather patterns.
Factors that influence the climate * Air Mass * Albedo (Reflectivity) * Altitude * Angle of Sunlight * Carbon Cycle * Clouds * Distance to Ocean * Fronts * Greenhouse Effect * Human Activity * Land Changes * Landmass Distribution * Latitude * Location * Mountain Ranges * Pollution * Precession * Rotation * Solar Output * Volcanoes * Wind Patterns

Air closest to the Earth’s surface is warmer and rises.
Air higher up in the atmosphere is colder and will sink.
Low-Pressure System * Low Pressure at the center. * Winds blow towards the low pressure. * Usually forms clouds and precipitation. * Produces cloudy and stormy weather.
High-Pressure System * Wind blows away from the high pressure. * Contain cool, dense air. * Usually associated with fair weather.
Coriolis Effect * Earth’s rotation on an axis causes winds to not travel straight.
Hadley, Ferrel, and Polar Cells * The worldwide system of winds.
Hadley Air Circulation Cells * Air heated near the equator rises and spreads out north and south. * After cooling in the upper atmosphere, the air sinks back down to the subtropical climate zone.
Ferrel Air Circulation Cells * Develop between 30 degrees and 60 degrees north and south latitudes. * Area where these circulation cells control contains broadleaf, deciduous, and coniferous evergreen forests.
Polar Air Circulation Cells * Icy-cold, dry, dense air that descends from the troposphere to the ground. * Air meets with warm tropical air and then returns to the poles. * Reason why polar areas are deserts.
Polar Vortex * Low-Pressure zone that lies above both poles. * Large Mass of Cold Air.

Hurricanes * Most severe weather phenomenon on the planet. * Warm areas over oceans where the trade winds converge. * Separate thunderstorms move in a circular motion. It allows them to pick up moisture and heat energy from the ocean. * Energy from the hurricane dissipates over land.
Tornadoes * Swirling masses of air.
Tornadoes vs Cyclones * Tornadoes are caused by a singular storm. * Cyclones are developed from multiple separate storms. * Tornadoes are over land. * Tropical Cyclones die out over land due to the lack of moisture.
Monsoons * Strong, violent winds that change direction with the season. * Blows from cold to warm regions.

La Nina * Normal Conditions * Easterly Trade Winds move water and air warmed by the sun towards the west. * Water in the Pacific is 14 degrees hotter.
El Nino (Warm Phase) * Air pressure reverses direction. * Causes extensive fish kills due to water moving away. * Ocean temperatures are their warmest. * Enhances convection.
El Nino (December - February) * Surface water returns to cooler, nutrient-rich water. * Supplies necessary nutrients to phytoplankton.
La Nina (Cold Phase) * Trade winds that blow west are stronger than usual. * Leads to wetter than normal conditions across the Pacific Northwest, and drier weather in the Southern United States. * Winter temperatures are warmer in the Southern United States and cooler in the northwest. * Causes heavier monsoons in Southeast Asia and India.