Heat & the Atmosphere:

Objectives:

1.    Describe how energy from the sun moves through the atmosphere by radiation, conduction and convection.

2.    Identify the characteristics of each layer of the atmosphere.

3.    Analyze Earth's heat budget.

Key Terms:

radiation    conduction    convection    temperature    heat    troposphere    stratosphere    ozone    mesosphere    thermosphere    ionosphere    insolation

Notes: (17.2)

How heat and energy moves

As you remember from earlier chapters Earth is a closed system in which the only thing that freely enters and leaves is energy.  This energy is obtained principally from the sun through radiation.  The Sun's energy is responsible for driving our weather and is essential to the core production of nutrients that feed all organisms on Earth.

The energy budget refers to the energy cycle on Earth where if we retain more than we give off our Earth warms and visa-versa.  Below are the means by which energy is transfered.

 Is how we get energy from the sun The energy is carried by eloctromagnetic waves The UV radiation is absorbed by the ozone Heats up the atmosphere IR radiation is absorbed at the surface Cannot escape atmosphere

## Conduction

 Energy transfer when atoms or molecules bump into one another By direct contact Energy transfer continues until both substances are the same temp

(kkd.ou.edu/conduction.jpg)

## Convection

 Is the transfer of heat in flowing currents in a liquid or gas Currents are caused by the difference in temperatures Hotter less dense molecules rise where they cool and condense and begin to sink

(www.ipgp.jussieu.fr/.../profondeur/ dynamique/convection.jpg)

Heat & Temperature

Energy is the term used to describe the capacity to produce heat or to do work.  There are two major forms of energy, Kinetic and Potential.

Kinetic Energy (KE)is the energy of motion.  When an object is in motion, it carries kinetic energy in the amount of 1/2 multiplied by the mass multiplied by the velocity squared.  (1/2mv2)  Kinetic energy can also come in the form of mechanical energy (energy created by the gears of a machine) and thermal energy (heat created by the internal motion of particles of matter).

Although heat and Temperature are related they are not the same

 Heat is the total kinetic energy of the particles in a substance (think friction) Temperature is the measure of the kinetic energy in a substance Although two items of the same composition and of different weights may have the same temperature, they have different amounts of heat

Structure of the Atmosphere:

Structure of the atmosphere - Arranged in layers

Troposphere (0-10km)

 Contains ~75% of the atmospheric gasses, solids and liquids Weather and clouds occur here Temperature decreases with altitude Tropopause separates it from the stratosphere

Stratosphere (10-50km)

 Ozone layer & Jet stream Temperature increases with altitude - due to absorption of radiation Stratopause separates it from the mesosphere

Mesosphere – middle (50-95km)

 Temperature decreases with altitude Mesoopause separates it from the thermosphere

Thermosphere (95-~250km)

 Contains the ionosphere – area of charged particles Very few particles Temperature increases with altitude - due to absorption of radiation Thermopause separates it from the exosphere

Exosphere - Outer limit of the atmosphere – (>250km above earth)

 Place of shuttle orbiting

(www.cimms.ou.edu/~cortinas/ 1014/A01_07.gif)

Heat Budget

The heat budget compares the amount of insolation (incoming solar radiation) to the amount of radiation leaving our atmosphere.  If our budget is in balance the temperature will remain fairly consistent (which is generally the case).  The retention of insolation is called the greenhouse effect.

Absorption & Reflection of Insolation

 30% reflected directly back to space +51% absorbed by the Earth -6% directly released back to space 45% into the atmosphere in the form of evaporation,         condensation, conduction and convection +19% absorbed by the clouds -64% eventually released to space through the atmosphere Total insolation = total radiation

(www.oceansonline.com/ images/greeneff.jpg)