Heating of the Earth

Review of Key Features of the Earth

Transfer of Solar Energy Conduction – energy transferred by direct contact (substance to substance) Convection – energy transferred by moving (place to place as a gas or liquid) Radiation – transfer of energy by electromagnetic waves

Examples of Conduction Spoon in a bowl of hot soup Metal marshmallow stick heating up

Conductors Substances that transfer thermal energy quickly and easily. Iron skillet Liquids and solids are good conductors because they have freely moving electrons Coils on stove Copper pipes Cookie sheet

Insulators Items that transfer energy poorly. Flannel PJ’s Oven Mitt Plastic spatula Gases are not good at transferring energy because particles are further apart and have fewer collisions Ceramic bowl Fiberglass

Examples of Convection Heated water becomes less dense and rises, boiling water Hot air expands and is less dense, hot air balloon Radiator heat

Examples of Radiation ELECTROMAGNETIC SPECTRUM - Spectrum shows the relative wavelengths of each type of radiation

Which gets hotter faster? Ocean water or beach sand Which gets hotter faster? Snow or dirt

Absorption & Reflection of Solar Energy What is effective at absorbing heat?

Which heats up faster, land or water?

Land Heats Up Faster Because… Solar energy only penetrates a few centimeters in soil, but up to 300 meters in water water has a much higher specific heat than rocks or soil. Convection currents in water moves the heat around

Specific Heat The amount of heat energy it takes to raise the temperature of 1 gram of a substance by 1 degree Celsius Low specific heat = heats up and cools off quickly (doesn’t take a lot of energy) High specific heat = heats up and cools off slowly (takes a lot of energy)

Greenhouse Effect Energy enters the atmosphere heating Earth’s surface Surface re-radiates the heat Greenhouse gases absorb this heat (infrared) Main greenhouse gases Carbon dioxide Water vapor

Is the Greenhouse Effect Good or Bad? GOOD - It is needed for life; it keeps our climate stable and warm. BAD - too many greenhouse gases causes climate to warm to much

Heat Transfer Quiz: Identify the type of Heat Transfer C B A A = Radiation B = Convection C = Conduction

Heating of the Earth Does the sun heat the earth evenly? No, its shape does not allow all places on the surface to receive the same amount of energy. Which area of the earth receives the most solar energy (heat)? Equator (most direct sunlight) Which area of the earth receives the least solar energy? The poles (least direct sunlight)

Heating of the Earth

Temperature & Air Pressure Uneven heating of Earth creates different air pressures (highs and lows). Air Pressure – Created by the number of air molecules moving and bouncing off an object. Measured using a barometer. Air pressure increases, mercury in tube increases. Examples: Warm air = more active air molecules = low air pressure Ex: equator Cool air = less active air molecules = high air pressure Ex: poles

Air Pressure – Created by the number of air molecules moving and bouncing off an object. (Measured using a barometer.)

Elevation & Air Pressure

High and Low Air Pressure Systems

Air Pressure & Moisture Low air pressure usually means warm humid weather (ex: equator). Why? Warm air causes more evaporation; air molecules are more active & can hold more moisture High air pressure usually means cooler drier weather. Why? Less evaporation; molecules are close together holding less moisture.

Low Pressure at Equator

Differences in Temperature & Air Pressure Remember: uneven heating of the Earth creates differences in air pressure. What do the differences in temperature and air pressure create? Wind How do they create wind? Air wants to move from an area of high pressure to an area of low pressure

Wind Direction

Sea & Land Breeze Convection Currents

Sea Breezes Coastal Areas Land surface heats up fast during the daylight hours Hot air rises Creates low pressure Wind blows from the sea to the land

Land Breezes Coastal Areas Land surface cools off fast during the night hours Cool air sinks Creates high pressure Wind blows from the land to the sea

Global Winds The uneven heating of the earth creating differences in air pressure creates global winds. At the poles: indirect solar energy; cold temps; high pressure air sinks and moves towards the equator. At the equator: direct solar energy; warm temps; low pressure air rises and moves towards the poles. The circular movement is called a convection current.

Complex Movement of Global Winds Why isn’t it as simple as one global wind convection current in each the northern & southern hemisphere? Earth’s rotation affects wind direction. The influence of the Earth’s rotation on the movement of air and water is called the Coriolis Effect. The Coriolis Effect cause global winds to turn: Northern Hemisphere = clockwise Southern Hemisphere = counter clockwise

Coriolis Effect

Global Wind Belts & Calm Regions