Warming of the Earth and the AtmosphereDr Thaer O. RoomiDept. of Atmospheric Sciences

Composition of AtmosphereGases

The magic gas= H2O (The vapor which is highly variable from place to place 0-4%)

Composition of AtmosphereImpurities Aerosols (Liquid and solid particles suspended)

1. Mineral Dust (Sand, Silt, Clay)2. Salt Particles3. Smoke, ash, smog, soot4. Viruses, Bacteria, spores, pollenPollutants(NO2, CO, Hydrocarbons, SO2 , O3 )

What is Temperature Simply is the quantity that tell us how hot or cold something is

relative to some set standard value. We can look at it differently:

This means that the air temperature is a measure of its average kinetic energy.

The molecules and atoms of air are in

motionHence, they have kinetic

energy

Increasing temperature

Increasing the speed

Increasing the kinetic

energy

More temperature, less density

Warming of air

More kinetic energy

Faster molecule

s

Molecules

Departure

Less density

Heat Transfer

Atmosphere contains INTERNAL Energy, which is the total energy stored in molecules.

Heat is the energy transferred from object to another because of the temperature difference between them.

After heat is transferred, it is stored as internal energy.

Heat is transferred by conduction, convection, and radiation.

Heat transfer

Conduction Is the transfer from molecule to molecule of substance.Heating solids causing the molecules vibrate

faster.The faster vibrating molecules cause adjoining

molecules to vibrate faster, and so on.Heat is flowing from the warmer to colder

regions.Air is extremely poor conductor of heat.In calm weather , the hot ground only warms a

shallow layer of air a few centimeters thick by conduction.

Heat transferConduction

Heat transferConvectionThe transfer of heat by the mass movement of a fluid (such

as water and air) is called convection. This type of heat transfer takes place in liquids and gases because they can move freely. Convection happens naturally in the atmosphere.

On a warm, sunny day certain areas of the earth’s surface absorb more heat from the sun than others; as a result, the air near the earth’s surface is heated by conduction.

The heated air expands and becomes less dense than the surrounding cooler air. The expanded warm air is buoyed upward and rises.

Heat transferConvection

Heat transferRadiationElectromagnetic waves release energy when they are

absorbed by an object.Electromagnetic waves do not need molecules to propagate

them. On a warm, sunny day certain areas of the earth’s surface

absorb more heat from the sun than others; as a result, the air near the earth’s surface is heated by conduction.

The heated air expands and becomes less dense than the surrounding cooler air. The expanded warm air is buoyed upward and rises.

Packets of photons make up waves, and groups of waves make up a beam of radiation.

Radiation

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: على نحص واالرض الشمس حالة من لكل فين قانون بتطبيق

Radiation

Since the sun radiates the majority of its energy at much shorter wavelengths than does the earth, solar radiation is often called shortwave radiation, whereas the earth’s radiation is referred to as longwave (or terrestrial) radiation.

THE EARTH’S ANNUAL ENERGY BALANCE

Solar Constant = 1361 W/m2

The earth-atmosphere energy balance

Greenhouse EffectGreenhouse effect caused by the trapping of the infrared earth radiation by water vapor and other greenhouse gases such as: Carbon dioxide, methane, Nitrous oxide, and CFCs.Clouds also contribute in the greenhouse effect.

Global Warming:The average temperature of the near surface air layers is getting hotter and hotter year by year because of the increasing of the greenhouse gases, especially CO2.

In the last 100 years, there was a 0.6o C increment above the average. Scientists believe that by the end of 2100, the increment will be 3.5o C.

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Is the existence of greenhouse gases is good or bad?Actually atmospheric greenhouse effect is essential to life. Without it, the mean temperature of the lower part of troposphere will be -18o C. The problem lies in the imbalanced excess of warming and this will lead to a significant CLIMATE CHANGE.

Latent heat (The effective source of Atmosphere’s Energy)

Latent heat (The hidden Warmth) is the heat energy required to change a substance, such as water, from one state to another. It is very important in formation of clouds, thunderstorms, and tropical storms.

Why we call it hidden?

Latent heat

Latent heat

During evaporation, the energy lost by liquid captured by the water vapor molecules. The energy is thus “stored” or “hidden”

It is latent (hidden) in that the temperature of the changing from liquid to vapor still the same.

However, the heat energy will reappear as sensible heat (the heat that we can feel it and measure it) when the vapor condenses back into liquid water.

Therefore, the condensation is warming process.Huge amount released into the environment by

latent heat

Heat energy absorbed and released

Thanks