1 Met 10 Weather Processes Jeff Gawrych Temperature, Heat Transfer and Earth’s Energy Balance

2 Lecture Outline Energy in the atmosphere Shortwave and longwave radiation Greenhouse effect Earth/atmosphere energy balance

3 Why does the earth heat up? Incoming solar radiation is absorbed by the surface of the planet. The amount and intensity of the solar energy received is called insolation. Some areas get more insolation than others. E.g. The tropics are generally warmer than the polar regions.

4 Heat Sensible Heat: he we feel Latent Heat: The heat energy required to change water from one state to another (e.g. water from a vapour to a solid). “hidden” heat due to phase changes –E.g. Water has 3 phases –1 ________ 2 _______ 3 ________ evaporationLatent heat of evaporation : –Heat lost to environment condensation:Latent heat of condensation: –Heat released to environment

5 Heat Sensible Heat: he we feel Latent Heat: The heat energy required to change water from one state to another (e.g. water from vapor to a solid). “hidden” heat due to phase changes –E.g. Water has 3 phases –1) Ice 2) Liquid 3) Vapor (gas) evaporationLatent heat of evaporation : –Heat lost to environment condensation:Latent heat of condensation: –Heat released to environment

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7 Earth’s Energy Balance A balance exists that keeps the planet from getting too hot or cold –Energy entering top of atmosphere must equal __________________________ –Energy entering the Earth’s surface must equal __________________________

8 Earth’s Energy Balance A balance exists that keeps the planet from getting too hot or cold Energy leaving top of atmosphere –Energy entering top of atmosphere must equal Energy leaving top of atmosphere Energy leaving Earth’s surface –Energy entering the Earth’s surface must equal Energy leaving Earth’s surface

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11 There are three modes of energy transmission in the atmosphere. Conduction: the transfer of energy in a substance by means of molecular excitation without any net external motion. Convection: the transfer of energy by mass motions within a fluid or gas, resulting in actual transport of energy. Radiation: the propagation of electromagnetic waves through space. Energy transmission

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Electromagnetic radiation Radiation is the transfer of energy by rapid oscillations of electromagnetic fields. The most important general characteristic is its wavelength ( ), defined as __________________________. Radiation travels through space at the speed of light (3 x 10 8 m s -1 ). All objects emit radiation!!!! Amount of radiation absorbed/emitted depends on ___

Electromagnetic radiation Radiation is the transfer of energy by rapid oscillations of electromagnetic fields. The most important general characteristic is its wavelength ( ), defined as the crest-to-crest distance. Radiation travels through space at the speed of light (3 x 10 8 m s -1 ). All objects emit radiation!!!! Amount of radiation absorbed/emitted depends on Temp.

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18 Short and longwave radiation All objects emit radiation: –Sun emits radiation mostly at shorter wavelengths; ultraviolet (UV) and visible: ___________________________ –Earth emits radiation mostly at longer wavelengths; infrared (IR) ___________________________ Difference based on temperature of emitting body.

19 Short and longwave radiation All objects emit radiation: –Sun emits radiation mostly at shorter wavelengths; ultraviolet (UV) and visible: –Earth emits radiation mostly at longer wavelengths; infrared (IR) Difference based on temperature of emitting body. – –(shortwave or solar radiation) – –(Longwave or terrestrial radiation)

21 Atmospheric Greenhouse Effect Essential for life as we know it!!! The atmosphere absorbs some of the Earth’s outgoing longwave radiation. –Atmosphere acts like a blanket Which atmospheric gases are most responsible for the Greenhouse Effect? Runaway greenhouse effect

22 Atmospheric Greenhouse Effect Essential for life as we know it!!! The atmosphere absorbs some of the Earth’s outgoing longwave radiation. –Atmosphere acts like a blanket Which atmospheric gases are most responsible for the Greenhouse Effect? Water, Carbon Dioxide (CO 2 ) Runaway greenhouse effect –The addition of too many greenhouse gases that could possibly lead to large-scale climate change (global warming) –It is analogous to closing a window, in that outgoing radiation cannot escape.

25 Incoming solar radiation Each ‘beam’ of incoming sunlight can be either: –Reflected back to space: ________ Clouds Atmosphere Surface –Earth’s Albedo is ___% –Or absorbed; either by atmosphere (e.g. clouds or ozone) or Earth’s surface.

26 Incoming solar radiation Each ‘beam’ of incoming sunlight can be either: –Reflected back to space: albedo=reflectivity Clouds Atmosphere Surface –Earth’s Albedo is 30 % –Or absorbed; either by atmosphere (e.g. clouds or ozone) or Earth’s surface. –Or Scattered; This is why the sky is blue, or red, or whatever color. Whichever color you see if the most scattered wavelength (color) of visible light

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28 Earth’s Energy Balance The earth must stay in balance or else it would forever get hotter or colder. Energy into the Earth/Atmosphere system = Energy out of the Earth/Atmosphere

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