Earth's atmosphere

• As height increases in the atmosphere, the pressure and density of the air decreases
• the troposphere is the densest layer of the Earth's atmosphere, extending to about 16 km above the surface. Majority of the atmosphere's oxygen, nitrogen, and water vapor are here. Weather occurs here adn temperatures vary throughout different areas of the Earth.
• The stratosphere extends from 16-50km above sea level. The ozone layer is found here which absorbs most of the UV radiation in the atmosphere that would otherwise reach the surface. Temperatures increase with altitude due to absorption of solar energy by O3 molecules. This layer protects life on earth from damaging ultraviolet rays.
• The mesosphere extends from 50-85km above sea level. It is the coldest layer. Meteors burn up here as they enter the Earth's atmosphere.
• The thermosphere extends from 85-700km above sea level. Most satellites orbit within this region. In this layer, temperatures increase with altitude due to absorption of highly energetic solar radiation. It is crucial in protecting the Earth from X-ray and UV radiation. It is also where the northern and southern lights occur.
• The exosphere where the atmosphere blends into space and never technically ends since space is inifinite
• First property of unequal heating: Areas near the Equator receive direct, perpendicular light. Areas nearer the poles receive angled, oblique light that has to travel further through the atmosphere, losing energy
• Second property of unequal heating: Direct light will also cover a small surface area, releasing more energy per area. The indirect light will diffuse and cover a larger area, releasing less energy per area.
• Third property of unequal heating: albedo - percentage of incoming solar energy reflected. The higher the albedo, the more energy it reflects which means it is covered with more snow and therefore the colder the surface.
• During the summer solstice, the northern hemisphere is tilted towards the sun, allowing for longer days with direct sunlight.
• The equniox is when the the sun is directly overhead at the equator and all regions on Earth receive 12 hours of daylight and 12 hour of darkness. There are two equinoxes per year. One is in September(northern enters fall and southern enters spring) and another is in March.
• Air current/Convection currents


  Unequal heating affects how air moves, distributing heat and mositure with it
• Four factors of air currents/circulation: density, saturation point, adbiatic heating and cooling, latent heat release
• Air current factor 1: Density: Warm, less dense air rises while cooler, denser air sinks. Chemical make-up(what gases are present. E.g. concentrations of CO2) will also impact air density
• Air current factor 2: Saturation Point: the max amount of water that can be in air at a given temperature. Warmer, less dense air has a higher saturation point(think of humidity). The capacity for air to contain water vapor impacts air flow. Air can only hold so much moisture until it reaches its saturation point where water vapor condenses into clouds. This causes precipitation to occur.
• Air current factor 3: Adiabatic Heating & Cooling: as air rises or sinks,

  the pressure changes.Increased pressure forces molecules closer together, warming them. Decreasing pressure spreads molecules apart, cooling them
• Air current factor 4: Latent Heat Release: when Water evaporation occurs, heat is released as it changes from liquid water to gas(water vapor or clouds). It warms the surrounding air and increases humidity levels. The sun provides the energy and heat to evaporate water and turn it into warm vapor.
• Hadley cell: convection current in the atmosphere that cycles between the equator and 30 degrees N/S. Warm, humid air from the equator rises and expands due to latent heat release, creating clouds and causing for precipitation. the air has lost water and is cold, and moves to 30 N/S and sinks. As it sinks, adiabatic heating causes the dry air to warm. This causes hot, dry deserts such as the sahara at 30 N/S. After the warm air returns to to the equator and the cycle repeats.
• Ferrell cell: lies between hadley and polar. Air currents are driven by the circulation of neighboring polar and hadley cells. Air flow and direction can change depending on conditions or season
• Polar cell: convection currents formed by air that rises at 60 N/S and it cools, condenses, and precipitates. The cold air dries and sinks at the poles. The air in the circulation of the polar cell is always cold.
• Coriolis Effect: the deflection of an object's path due to the Earth's rotation. It deflects(change direction) moving objects( such as molecules in a mass of air) in a counter-clockwise direction in the northern hemispher eand a clockwise direction in the southern hemisphere. As convection currents flow, the Earth rotates underneath them, causing the direction of the air masses to curve. The Equator rotates at a faster speed than the poles, due to its circumference. This will cause greater degrees of deflection closer to the Equator
• Prevailing Winds: (of a region) winds blowing predominantly from a direction. they are causd by a combo of atmospheric convection currents and the Coriolis Effect
• Windward side: mountain side facing humid winds. It usually faces a body of water like the ocean. There is usually lots of vegetation here from rain
• Leeward side: mountain side facing away from humid winds. It is a dry, desertlike area.
• Rain Shadow: a region wtih dry conditions found on the leeward side of a mountain range as a result of the windward side blocking humid wind and therefore rain from reaching the leeward side.