The Atmosphere & Hydrosphere

Atmosphere Formed after the lithosphere –Gasses rose from the ground in the form of steam and volcanic eruptions 79% Nitrogen, 20% Oxygen, 1% Other gasses Has layers –Troposphere –Stratosphere –Mesosphere –Thermosphere (Ionosphere)

Why Important? Provides Oxygen and Carbon Dioxide Traps in heat and stabilizes temperature around the globe Re-circulates water Shields living things from Ultra-Violet light.

Air Pressure This is the mass of air pressing down The higher the altitude, the lower the pressure (less air pushing down) Hot places have lower pressure than cold places Wind blows from high to low pressure areas

Troposphere 75% of Atmosphere’s mass 95% of Atmosphere’s water vapour Where all weather occurs Strong air currents At higher altitudes air becomes: –Cooler –Thinner –Drier

Stratosphere Air flow is stable (horizontal) This is where most airplanes fly (avoid turbulence) Ozone Layer at the top filters UV light Gets hotter with increased altitude because ozone absorbs heat Not much water so very few clouds

Mesosphere 50-83kms above Earth’s surface Temperature gets colder as altitude increases. (down to -90 to -100 Celsius) Difficult to study –Too high for balloons and planes –Too low for satellites Air doesn’t move much here Most asteroids burn up in this layer

Noctilucent Clouds in Mesosphere

Thermosphere Between 90kms to 600kms above the planet Air is very thin (looks like outer space) International Space Station orbits Earth in the thermosphere Temperature rises very high ( Celsius) Contains Ionosphere which has –Radio waves –Aurora Borealis

Hydrosphere

70% of Earth’s surface is covered in water Roughly 1.36 billion cubic km of water Most in liquid form 2 nd most in ice form –If all ice were to melt, sea levels would rise 70m Most organisms are at least 60% water

Reservoir Volume (cubic km x 1,000,000) Percent of Total Oceans Ice Caps and Glaciers Groundwater Lakes Soil Moisture Atmosphere Streams and Rivers Biosphere

Dihydrogen Monoxide

Water…isn’t it great? Water has some very important attributes: –Gets larger as it cools –Absorbs large amounts of heat energy and releases it slowly –Has a neutral pH (Not acidic or basic) –Can remain a liquid across a wide temperature range (0-100 degrees Celsius) –Universal solvent –High Surface tension

Not only that but… Water molecules are the only substance on Earth that exists in all three states naturally (solid, liquid, gas) Through these changes massive amounts of heat energy is released ¾ of the heat trapped in the atmosphere is a result of evaporation

Evaporation Process by which liquid is converted to gas Requires that the atmosphere has less humidity than the evaporating surface –In 100% humidity no more evaporation occurs Requires large amounts of heat energy

Condensation Occurs when cooling Water vapour converts back to liquid This releases large amounts of heat energy

Oceans Hold the most water % of total Atmospheric winds affect the currents and heat near the surface Absorbs 90% of the heat energy that hits it Distributes this energy in the atmosphere through evaporation Ocean currents also distribute heat to cold areas like the poles