Earth’s Energy BudgetEarth’s Energy Budget

Modes of Energy TravelModes of Energy Travel

Heat Energy can be transferred in Heat Energy can be transferred in three specific ways:three specific ways:

ConductionConductionConvectionConvectionRadiationRadiation

Heat TransferHeat Transfer

ConductionConduction - transfer of energy from - transfer of energy from atoms that collide with other atoms (occurs atoms that collide with other atoms (occurs in earth materials and metals)in earth materials and metals)

ConvectionConvection – atoms in a gas or liquid – atoms in a gas or liquid transfer heat by moving vertically in a transfer heat by moving vertically in a space (a convection oven)space (a convection oven)

Radiation –Radiation – transfer of energy through transfer of energy through waves. This is how sunlight gets to earth.waves. This is how sunlight gets to earth.

Solar EnergySolar Energy When radiant solar energy reaches the Earth, 2 When radiant solar energy reaches the Earth, 2

different interactions occur:different interactions occur:ReflectionReflection – the radiation is reflected back – the radiation is reflected back

into space unchangedinto space unchangedAbsorptionAbsorption – the radiation is absorbed by – the radiation is absorbed by

the atmosphere of the Earth’s surface.the atmosphere of the Earth’s surface.70% absorbed70% absorbed30% reflected30% reflected

BreakdownBreakdown

Earth’s “Constant” TemperatureEarth’s “Constant” Temperature

The Earth retains a relatively constant The Earth retains a relatively constant temperature.temperature.

To do this, it must lose as much energy To do this, it must lose as much energy back to space as it absorbs from the Sun.back to space as it absorbs from the Sun.

Energy and WaterEnergy and Water

Most of the sun’s energy hits water on earth Most of the sun’s energy hits water on earth (earth is 70% water)(earth is 70% water)

Interactions between the sun’s energy and water Interactions between the sun’s energy and water have a major influence on weather but it have a major influence on weather but it depends on what state the water is independs on what state the water is in

White snow reflects up to 90% of the incoming White snow reflects up to 90% of the incoming solar energysolar energy

Ice reflects about 50%Ice reflects about 50%

Energy and WaterEnergy and Water

Liquid water reflects only about 7% (i.e. it Liquid water reflects only about 7% (i.e. it absorbs about 93%!!!) absorbs about 93%!!!)

Therefore many weather systems are Therefore many weather systems are initiated from the energy that is absorbed initiated from the energy that is absorbed by the oceansby the oceans

Water in the AirWater in the Air

Water exists in the air as a gas (water Water exists in the air as a gas (water vapour)vapour)

When the air becomes saturated, When the air becomes saturated, condensation of the water vapour occurs condensation of the water vapour occurs (forms liquid water droplets)(forms liquid water droplets)

The amount of water vapour in the air is The amount of water vapour in the air is measured by measured by humidityhumidity

The Water CycleThe Water Cycle

The incoming sun causes ~23% of liquid The incoming sun causes ~23% of liquid water to evaporatewater to evaporate

Evaporation occurs from all bodies of Evaporation occurs from all bodies of water but mostly the oceanswater but mostly the oceans

Evaporation occurs from plants through Evaporation occurs from plants through their leaves through a process called their leaves through a process called transpiration (or evapotranspiration)transpiration (or evapotranspiration)