Heating Earth’s Surface and Atmosphere The Atmosphere 10e Lutgens & Tarbuck Power Point by Michael C. LoPresto

Solar Energy Solar Energy Solar (sun) energy is heat energy. Heat energy is just one of many forms of energy: mechanical, kinetic, radioactive, electrical, chemical… Solar energy is not distributed evenly on Earth. It varies with latitude, time of day, and season. Solar Energy

What causes the seasons?

The Earth has Seasons because….. The length of the day changes during our orbital year. Angle of the sun changes during our orbital year. The amount of solar energy we receive changes during our solar year. This is because we are TILTED 23.5 ° on our axis

Sun Angle Variation with Latitude Is Due to the Tilt of Earth’s Rotational Axis

Sun Angles Vary with Latitude

High Sun Angles in the Tropics

Medium Sun Angles at Midlatitudes

Low Sun Angles in the Arctic

The angle affects the amount of solar energy that is received Concentrated into a small area Spread-out into a larger area

When solar energy reaches Earth it is either Insolation Earth receives only about one two-billionth of the suns total solar energy. Incoming solar radiation is called insolation. When solar energy reaches Earth it is either 1. absorbed, 2. reflected / scattered, 3. transmitted through 4. re-radiated

The thickness of the atmosphere varies by latitude. The thicker the atmosphere, the more the sun’s energy is absorbed, reflected or scattered. Which decreases intensity.

Incoming Solar Radiation? What Happens to Incoming Solar Radiation?

Reflection and Scattering of Sunlight Small dust particles and gas molecules in the atmosphere scatter some incoming radiation in all directions. (This explains how light reaches into the area beneath a shade tree, and how a room is lit in the absence of direct sunlight.) Scattering also accounts for the brightness and even the blue color of the daytime sky. (In contrast, bodies like the moon and Mercury—which are without atmospheres—have dark skies and “pitch-black” shadows even during daylight hours.) About half of the solar radiation that is absorbed at Earth’s surface arrives as scattered light.

Energy (pg. 41) Energy is defined as…. The capacity to do WORK Energy MOVES MATTER Energy can take many forms: chemical, heat, gravitational, electrical, nuclear Energy can CHANGE from one form to another.

2 Types of Mechanical energy Kinetic Energy: Energy of MOTION Potential energy STORED energy with the potential to do work. Due to a high position.

Temperature A quantity that describes how warm or cold an object is… compared to a standard scale 3 scales: Fahrenheit ((U.S.), Celsius, Kelvin Measure of the AVERAGE kinetic energy of the atoms in a substance

A thermometer measures its own temperature!

Incoming Solar Radiation? What Happens to Incoming Solar Radiation?

Albedo: percent of solar energy that is REFLECTED (based on the characteristics of the surface material)

Reflection from Surfaces of Different Albedo

Albedo 1. List two surfaces that have HIGH albedo: 2. List 2 surfaces that have a LOW albedo:

Incoming Solar Radiation? What Happens to Incoming Solar Radiation?

HEAT The transfer of energy from one object to another or its surroundings due to a temperature difference Heat always flows from high temperature to lower temperature Until the temperatures become equal – thermal equilibrium

Heat Transfer Heat energy can be transferred from the Sun to the atmosphere to the earth in one of three ways: Conduction Convection Radiation

Mechanisms of Heat Energy Transfer

Convection Transfer of heat energy through a liquid or gas Convection Transfer of heat energy through a liquid or gas. Is due to different density of the liquid or gas. Warm air is less dense and it rises- Cool air is more dense and it sinks. (Remember thermal convection in the mantle…?)

Conduction Transfer of energy through collisions from faster moving molecules to slower moving molecules. Air is a poor conductor of heat, Conduction occurs only between the hot surface and the air immediately above it.

Radiation Transfer of energy through space in the form of electromagnetic radiation. UV Infrared (heat) Visible light Microwave Gamma X-ray

Electromagnetic Radiation The Electromagnetic Spectrum

Ultraviolet Radiation UV Index monthly values around the globe

Radiation from the Sun and Earth

Absorptivity of Atmospheric Gases Gases are selective absorbers Nitrogen -poor absorber Oxygen and Ozone- good absorber of UV

How we experience most of the heat on Earth:

So…. Our atmosphere does NOT get it’s heat directly from sun, But mostly from energy that is first absorbed by the earth’s surfaces- then re-adiated as radiant heat

So what is with our Greenhouse Gases? Especially CO2… ultraviolet infrared http://phet.colorado.edu/en/simulation/greenhouse

Infrared Imaging

Clouds and Heating Earth

Solar Power

Earth’s atmosphere is TRANPARENT to the ultraviolet photons of energy from the sun. The photons of infrared energy re-radiated by the Earth will either be ABSORBED or REFELCTED by these gases therefore trapping some heat close to the Earth’s surface.

Heat Budget of Earth’s Atmosphere

The Rise of CO2…

Temperatures Rise…

Calculating Solar Intensity

a. Conduction b. convection c. Radiation A ceiling fan circulates warm air in a room. Walking barefoot on a hot parking lot Drying a beach towel on the deck. Warming in front of a fire place. Getting sunburned at the Cubs game. Burning your foot on used sparkler that was left in the grass.

Heat or Temperature? Thermometer measures…. Total kinetic energy of all the molecules.

List 3 factors that effect the amount of insolation 1. 2. 3.

Global Warming and Rising Sea Levels Eskers The long, winding ridges that formed when sub-glacial streams filled with sand and gravel sediments deposits

What’s Causing Global Warming? Top of Atmosphere  Heat Incoming  Heat Outgoing  Net Heat Input Causes Global Warming

What’s Causing Sea Level Rise? Ice Melt More Water, More Mass  Thermal Expansion, More Volume Heat  Sea Level Rise

Sources of Ice Melt & Potential Impact on Sea Level Antarctica 6 m Greenland 0.7 m Mountain Glaciers

Ross Ice Shelf, Antarctica is a huge ice sheet “floating” out on top of the more dense Pacific Ocean salt water

Why Measure Sea Level Rise? Inundation Will Have a Catastrophic Impact