Energy = the ability to do work Two Energy Categories: 1. Kinetic Energy (energy of motion) Types: – Electromagnetic energy (from our Sun) – Light energy – Thermal (heat/infrared) energy – Mechanical (motion) energy – Sound – Electrical energy 2. Potential Energy (stored energy) Types: – Chemical energy – Nuclear energy – Gravitational energy

The sun is our greatest energy source The Sun transfers potential energy (nuclear) to kinetic energy (light, heat). This energy reaches Earth as INSOLATION. INcoming SOLar radiATION

Sun’s Energy Created by nuclear fusion (Potential  Kinetic) The Sun (stars) emits electromagnetic energy which is radiated in the form of TRANSVERSE waves. – All electromagnetic energy travels at the speed of light (3.0 x 10 8 m/second or 186,000 miles/second). – The different types of electromagnetic energy are due to their difference in wavelength and frequency.

Electromagnetic Energy Wave Terminology Characteristics of Waves Parts of a wave – Crest is the top of the wave (high point) – Trough is the low area between waves (low point)

Electromagnetic Energy Wave Terminology Characteristics of Waves Measurements of a wave – Amplitude is the height of a wave crest or trough. – Wavelength is the horizontal distance between crests or troughs.

Electromagnetic Energy Wave Terminology Characteristics of Waves Measurements of a wave – Frequency is number of waves passing a certain point during a period of time.

Incoming Solar Radiation Figure 2.8

What happens to this insolation when it reaches Earth? Insolation (energy) gets: – Reflected (31% gets reflected back into space by atmosphere) Albedo = value use to measure surface’s reflectivity – Refracted Change in speed and direction of light – Scattered Changing direction of light’s movement, without altering its wavelengths – Absorbed in Atmosphere and Earth’s surfaces (land/water) Amount of energy absorbed is – Dependent on the material’s Specific Heat (look at your E.S.R.T.) – Dependent on material’s color and texture

Reflection

refracted – bent Glass of Water

Refraction Figure 4.3

Reflection & Refraction due to ice crystals in our atmosphere Resulted in Halos in this image.

Absorption of Energy on Earth Most of the Sun’s energy absorbed by Earth atmosphere and surfaces is visible light: – Lighter colors will reflect more and absorb less energy – Darker colors will absorb more and reflect less energy – Smoother surfaces will reflect more energy – Rougher surfaces will absorb more energy

Transfer of Heat Heat flows from a region of higher energy (Heat Source) to a region of lower energy. (Heat Sink) Heat is created by the internal motion of molecules.

Methods of Heat Transfer Radiation – Energy traveling through air or space (no medium of transmission is required)

Methods of Heat Transfer Conduction – Molecule to molecule energy transfer in a gas, liquid, or solid (BEST IN SOLIDS) – Requires contact between two things (for example: a stove and a pot) Conduction

Methods of Heat Transfer Convection – The transfer of heat energy in a LIQUID or GAS through the circulatory movements (currents) of heated particles within the substance. – Convection Cell – A circulation system of motion within a liquid or gas in which temperature and density differences exist.

Heat Transfer in the Atmosphere Conduction – Molecule to molecule energy transfer in a gas, liquid, or solid Convection – The transfer of heat energy in a liquid or gas through the circulatory movements (currents) of heated particles within the substance. – Convection Cell – A circulation system of motion within a liquid or gas in which temperature and density differences exist. Radiation – Energy traveling through air or space (no medium of transmission required)

Specific Heat Ability of a material to increase in temperature (amount energy to raise 1 gram of a material 1°C). – The higher an object’s specific value; the slower a material will increase in temperature example: Iron=.45 Joules/gram °C Liquid water=4.18 Joules/gram °C Therefore iron will heat up quicker than liquid water because less energy is required to raise its temperature 1 °C

Specific Heat Materials with high specific heats take more time to heat and cool than materials with low specific heats. Liquid water has the highest specific heat! – See ESRT page 1!

Phase changes Melting solid to liquid Evaporation liquid to gas Freezing liquid to solid Condensation vapor to liquid Sublimation solid to gas gas to solid

Latent Heat A form of potential energy which is absorbed or released as a phase change is occurring. - No temperature change on the thermometer during a phase change!

Insolation and Factors that Affect It Insolation (INcoming SOLar radiATION) – the portion of the sun’s output of electromagnetic energy that is received by the Earth at the top of our atmosphere. Direct Insolation –when the sun’s rays strike the Earth at a 90 o angle; the sun is at the zenith at solar noon

Variation in Insolation Insolation can vary by intensity (strength) and by duration (length of time), which are controlled by the Earth’s shape, latitude, seasonal changes, and time of day. More intense insolation – near Equator and Tropics Less intense insolation – near Polar areas

Seasonal Changes in Insolation The location of the maximum (direct) insolation changes based on day of the year: June 21 st = 23.5 o N March 21 st /Sept 23 rd = 0 o (equator) December 21 st = 23.5 o S

Do we ever have “direct insolation” in New York State? NO!

The highest angle and intensity of insolation during any day is at Solar Noon and the lowest angle/intensity is at sunrise and sunset!

Daylight Hours

Duration of Insolation = length of time that insolation is received during each day. In the NH, the duration of insolation is longest on June 21 st (approximately 15 hours) and shortest on December 21 st (approximately 9 hours). The duration is 12 hours on the equinoxes.

The Tilt of Earth’s Axis – The tilt results in a varying angle of insolation; the direct rays shift between 23.5 o N and 23.5 o S latitude. Parallelism of the Earth’s Axis – regardless of its position in orbit, the Earth’s axis always points in the same direction in space (towards Polaris).

Revolution of the Earth Around the Sun – As the Earth revolves around the sun, the direction of the Earth’s axis with respect to the sun varies because of its tilt and parallelism

Global Heat Budget Those two most important words in Earth Science…. Dynamic Equilibrium – the system is in balance, even though there is constant motion Do these numbers balance out?

The Greenhouse Effect and Atmospheric Warming Earth’s Natural Process of keeping our planet warm. – Gases in our atmosphere trap heat energy (infrared) from escaping into space too quickly. Our Atmosphere – allows visible light through (shorter wavelength) – Traps infrared energy (LONGER WAVELENGTH)

Greenhouse Effect Short wavelength of electromagnetic energy enters the greenhouse then is absorbed inside, and then re-radiated as longer wavelength infrared (heat). The glass similar to our atmosphere allows shorter wavelength of energy and traps the infrared (heat) energy.

Greenhouse Effect In the atmosphere, CO 2 and H 2 O, methane, nitrous oxides are the greenhouse gases act like the glass in the greenhouse by trapping heat. CO 2 and H 2 O (greenhouse gases) absorb infrared that is re-radiated from the surface of the Earth. Therefore, gases trap heat in the atmosphere and raise the global temperature.

IMPORTANT! The greenhouse effect is a natural process that leads to an Earth which is warmer (it would be 33°C cooler without it) It is the reason that our Earth is warm enough to live on It is a GOOD thing for life on this planet