Heat transport Water cycle Atmospheric circulation Processes forcing the climatic conditions

Radiation There are four main processes of energy transport in the atmosphere: radiation, molecular conduction turbulent conduction latent heat sensible heat

Thermal Energy  All matter is composed of atoms or molecules, which are in constant motion  Molecular or atomic motion = “thermal energy”  Heating atoms causes them to move faster, which represents an increase in thermal energy.  Temperature is a measure of thermal energy.

Radiation is the way of energy transport by electromagnetic wave moving with the speed of light. It does not demand any medium. Energy is transmitted in portions called kwantums. wavelength × frequency = speed of light wavelength crest through

Energy of a wave Energy is proportional to frequency, and inversely proportional to wavelength E = h = h (c/ ) where h = Planck’s constant In other words, waves with shorter wavelengths (or higher frequency) have higher energy

Each body with temperature higher than 0K (-273,13ºC) emits radiation to space, ie. emits an electromagnetic wave moving with the speed of light differing in wavelength, frequency and amplitude.

All bodies, with temperature greater than absolute 0, emit radiation. The rate at which something radiates and absorbs energy depends strongly on its surface characteristics, such as color, texture, moisture and temperature. There is a group of bodies called black bodies. The rate at which they radiate energy depends only on their temperature. They are perfect absorber of radiation (absorb all radiation that strikes them) and a perfect emitter (emit the maximum radiation possible at their temperature).

Blackbody Radiation Blackbody radiation—radiation emitted by a body that at all wavelengths emits (or absorbs) energy in the amount described by law of Planck. Law of Planck

Basic Laws of Radiation 1)All objects emit radiant energy.

Basic Laws of Radiation 1)All objects emit radiant energy. 2)Hotter objects emit more energy than colder objects.

Basic Laws of Radiation 1)All objects emit radiant energy. 2)Hotter objects emit more energy than colder objects. The amount of energy radiated is proportional to the temperature of the object raised to the fourth power.

Basic Laws of Radiation 1)All objects emit radiant energy. 2)Hotter objects emit more energy than colder objects. The amount of energy radiated is proportional to the temperature of the object raised to the fourth power.  This is the Stefan Boltzmann Law E =  T 4 E = flux of energy (W/m 2 ) T = temperature (K)  = 5.67 x W/m 2 K 4 (a constant)

Basic Laws of Radiation 1)All objects emit radiant energy. 2)Hotter objects emit more energy than colder objects (per unit area). The amount of energy radiated is proportional to the temperature of the object. 3)The hotter the object, the shorter the wavelength ( ) of emitted energy.

Basic Laws of Radiation 1)All objects emit radiant energy. 2)Hotter objects emit more energy than colder objects (per unit area). The amount of energy radiated is proportional to the temperature of the object. 3)The hotter the object, the shorter the wavelength ( ) of emitted energy.  This is Wien’s Law max  3000  m T(K)

 Stefan-Boltzmann law E =  T 4 E = flux of energy (W/m 2 ) T = temperature (K)  = 5.67 x W/m 2 K 4 (a constant)  Wien’s law max  3000  m T(K)

The amount of energy emitted by the black body at wavelength is depends only on the object temperature and is described by Planck's law: k Bolzmann's constant (k=1,38· J/K) T temperature in Kelvin scale c – speed of light (3,0·10 8 m/s), h - Planck's constant (h=6,63· J·s),

solar spectrum Earth's spectrum

We can use these equations to calculate properties of energy radiating from the Sun and the Earth. 6,000 K 300 K

T (K) max (  m) Part of spectrum E (W/m 2 ) Sun6000 Earth300

T (K) max (  m) Part of spectrum E (W/m 2 ) Sun Earth30010 Wien’s law: max  3000  m T(K)

T (K) max (  m) Part of spectrum E (W/m 2 ) Sun Visible (yellow?) Earth30010infrared

T (K) max (  m) Part of spectrum E (W/m 2 ) Sun Visible (green) 7 x 10 7 Earth30010infrared460 Stefan-Boltzmann law: E =  T 4

wavelength energy Sun Earth Hotter objects emit more energy than colder objects E= σT 4

wavelength energy Sun Earth Hotter objects emit at shorter wavelengths. max = 3000/T

Outgoing Longwave Radiation (OLR) Anomalies Wetter-than-average conditions (blue shading) Drier-than-average conditions (orange/red shading) From October – December 2011, variability in OLR anomalies (focused mostly over the Indian Ocean and Maritime Continent) was associated with the MJO. Since April 2010, negative OLR anomalies have been observed near the Maritime Continent and positive OLR anomalies have prevailed over the western and central Pacific. Recently, eastward propagation of negative OLR anomalies is evident in association with the MJO. Longitude Time Climate Prediction Center / NCEP

UV visible light infrared radiation wavelength

Intensity of solar radiation at the upper boundary of the atmosphere is called solar constant and amounts on average 1353 W/m 2. Solar constant is not perfectly constant. The elliptical path of the Earth around the Sun brings the Earth closer to the Sun in January (147 mln km in aphelium) than in July (152 mln km in perihelium). From this reason the changes in solar constant during the year are about 3.5%. Since 1978 the remote sensing has been measured. It appears that the solar constant is also changing with solar activity. These changes did not exceed the level of 0.08% during the 30 years of measurements. In very long time scale (thousands of years) the orbital parameters of the Earth path around the Sun cause some changes in solar constant. The intensity of solar radiation is also changing in the long history of the Earth. 3.5 billions of years ago the Sun emitted only 70 % of radiation it is emitting today.

Solar radiation is emitted in each direction equally. Because the distance from the Sun to the Earth is really huge than the radiation reaching the surface is parallel. The amount of energy reaching the earth surface in the time unit is called intensity of direct solar radiation. Radiation that strikes a surface at an angle is spread over a larger area than the radiation that strikes the surface directly.

1.All objects with temperature above absolute zero emit radiation. 2.The higher the object temperature, the greater the amount of radiation emitted per unit surface area and the shorter the wavelength of maximum emission. 3.The Earth absorbs solar radiation only during the daylight hours; however, it emits infrared radiation continuously, both during day and at night. 4.The Earth’s surface behaves as a black body, making it a much better absorber and emitter of radiation than is the atmosphere

absorption and emission reflection scattering

In the atmosphere the radiation can be: scattered, absorbed reflected. When sunlight strikes a very small objects such as air molecules and dust particles the light itself is deflected in all directions – forward, sideward and backward. It is called scattering. Scattering on a tiny particles was firstly described by English scientist lord Rayleigh ( ) and is called a Rayleigh scattering. i λ - intensity of scatttered radiation of wavelenght λ, I λ - intensity of direct radiation of wavelenght λ, k – coefficient of scattering.

Absorption During the absorption process, the infrared radiation is converted into internal energy. Gases in our atmosphere are selective absorbers. Ozone, for example, absorbs UV radiation, especially at wavelengths between 0.2 and 0.3 μm, and an infrared radiation at 9.6 V μm. Molecular oxygen absorb UV radiation below 0.2 μm. Water vapor and carbon dioxide absorb energy in the infrared wavelengths.

ABSORPTION in the ATMOSPHERE infrared visible During the absorption process, the absorbed radiation is converted into internal energy. Gases in our atmosphere are selective absorbers. Ozone, for example, absorbs UV radiation, especially at wavelengths between 0.2 and 0.3 μm, and an infrared radiation at 9.6 V μm. Molecular oxygen absorb UV radiation below 0.2 μm. Water vapor and carbon dioxide absorb energy in the infrared wavelengths.

Absorption of radiation by gases in the atmosphere gasabsorption wavelenghts oxygen O 2 0,01-0,2  m ozone O 3 0,2-0,3  m, 9,6  m water vapor H 2 O 0,81  m, 0,93  m, 1,13  m, 1,37-2,66  m,  6,26  m, 9-34  m carbon dioxide CO 2 2,3-3,0  m, 4,2-4,4  m, 12,5-16,5  m

White or shiny objects reflect sunlight from their surface.An object that reflects a great deal of radiation of sunlights absorbs (and emits) very little. The percent of radiation returning from the surface compared to the amount of radiation stiking it is called the albedo of the surface. surface or objectalbedosurface or objectalbedo fresh snow75-95%grassy field10-30% cloud (thick)60-90%dry, plowed field5-20% cloud (thin)30-50%water10% ice30-40%forest3-10% sand15-45%

Earth surface radiation balance incomeoutcome direct radiation direct radiation falling on flat surface scattered radiation total radisation falling on flat surface solar radiation absorbed by the Earth surface radiation emitted by the Earth radiation transmitted downward efective radiation of the Earth

Daily course of temperature and balance of radiation

The Earth annual radiation balance and temperature course

Influence of ground cover type on heat balance sensible heat used for warming of the air net radiation input latent heat used for evapotranspiration exchange with the ground

Types of heat balance

Differences in heating of land and water surfaces transparency type of conductivity (turbulent or no) transpiration losses specific heat

comparison of maritime and continentals climates the temperature range the shift of maximum temperature

Questions and problems: 1. Describe some of the transformations energy goes through as water evaporates from the ocean. 2. How does the temperature of the object influence the radiation that it emits? 3. If the Earth's surface continually radiates energy, why it does not became colder and colder? 4. In the northern latitudes the oceans are warmer in summer than they are in winter. In which season do the oceans lose heat most rapidly to the atmosphere by conduction? Explain. 5. If all of the greenhouse gases were removed from the Earth's atmosphere, how would this influence the Earth's average temperature? Explain

How to explain glaciations? Tjeerd van Andel Nowe spojrzenie na starą planetę, PWN, 1997 Chapter 5 8th November 2012