13.2 Energy Systems

How Energy is Transferred Energy (heat or light) is transferred in one of the following ways: Radiation Convection Advection Conduction

Radiation The transfer of energy by electromagnetic (light) waves (electromagnetic spectrum) Does not require a medium to travel through (i.e. can travel through a vacuum) Travels in straight lines Is emitted (given off) by all matter The only form of energy given to us by the sun.

Solar Energy Where does it come from? produced by nuclear fusion reactions in the sun How does Solar Energy reach Earth? Radiant energy travels in waves of different energy levels, collectively known as the Electromagnetic Spectrum In order from lowest to highest energy level: Radio Microwave Infrared Visible Ultraviolet X-rays Gamma

Electromagnetic Spectrum

Convection transfer of energy by vertical movement of particles in a fluid (liquid/gas) as the particles gain energy they move faster, take up more space, become less dense, and then can rise through the fluid they are in this can create convection currents this method of heat transfer is very important to weather

Advection Transfer of energy through the collision of particles in a liquid or gas Energy moves horizontally

Conduction the transfer of energy which occurs when a particle with high energy hits a particle with lower energy energy is passed through an object from atom to atom only occurs in solids, since the particles must be close together for frequent collisions to occur readily

What energy is needed to survive on Planet Earth? Hint:

Albedo When solar energy strikes an object, some of the energy is absorbed and some is reflected Albedo is a measurement of the percentage of light which a material will reflect Polar Ice Cap – High or Low? Answer: High Black Roof – High or Low? Answer: Low Bare Soil – High or Low? The higher the albedo, the less energy absorbed.

Heat Capacity: A measure of how much heat a substance must absorb to increase its temperature by 1⁰ C. If a substance absorbs a lot of heat, yet its temperature rises slowly, then it has a high heat capacity. Think of the Yoho Lake & a sandy beach in the summer. they both absorb the same amount of heat The water stays cold because it can absorb a lot of heat without its temperature rising, the sand on the other hand gets very hot.

Heat Sink An object which absorbs energy and becomes warmer. A substance with a high heat capacity makes a good heat sink. Water has a high heat capacity and so is a good heat sink, while rocks have a low heat capacity.

Absorption and Reflection Solar energy entering the atmosphere can be either absorbed or reflected. Both absorption and reflection can occur with the air, clouds and the earth’s surface. approximately 70% in total is absorbed 44% heat the Earth’s land surface and air 25% heat the water and evaporate some water 1% creates wind Less than 1% is used for photosynthesis approximately 30 % is reflected (air 6%, clouds 20%, earth 4%) 30% of the sun’s rays are reflected back and do not reach the Earth 44% of the sun’s rays heat the Earth’s land surface and air 25% heat the water and evaporate some of the water 1% creates wind Less than 1% is used by Photosynthesis.

Why is Solar Energy Important? all forms of life on earth are dependent on solar energy for life needed for plants to grow and to keep earth warm enough for survival Reminder: less than 1% is used by Photosynthesis. PHOTOSYNTHESIS – The process by which green plants use sunlight to produce sugar. CO2 + 2H2O + sunlight ---> O2 + (C6H12O6)n + H2O or... carbon dioxide + water + sunlight ---> oxygen + carbohydrate + water

ENERGY MOVEMENT IN ECOSYSTEMS Chapter 1.11 Chapter 1.11

FOOD WEB – a series of interlocking food chains Of the less than 1% (0.023%), how does the energy disperse throughout food chains and food webs. When talking about food webs and energy, new terms are used to describe producers and consumers/decomposers. FOOD WEB – a series of interlocking food chains When talking about food webs and energy, new terms are used to describe producers and consumers / decomposers

AUTOTROPHS Plants or algae which make their own food using the sun’s energy through photosynthesis. Previously called producers.

HETEROTROPHS Animals, fungi and bacteria that must eat or decompose plants or animals ( and their waste) to get their energy. Previously called consumers / decomposers

WHY NEW TERMS? Each of the feeding levels ( consumer, primary consumer, secondary consumer ) is called a trophic level. Every time something is consumed in a food chain, energy is passed along. However, less and less energy is passed on each time because some of the energy is used for life processes (maintaining body temperature, digestion, growing, movement, etc)

ECOLOGICAL PYRAMID Number of Organisms Decreases Third Trophic level Secondary Consumers Available Energy Decreases Second Trophic Level Primary Consumers First Trophic Level Producers Energy from the Sun

With these new terms and previous old terms we can place labels on organisms within food chains and food webs. Lets look at Handout: Energy loss in a food chain

Energy Loss in Food Chains

ENERGY LOSS IN A FOOD CHAIN The higher the trophic level in the food chain, the more energy is lost. Consuming plants, which are the lowest trophic level, allows for the least amount of energy to be lost.

A SIMPLE FOOD WEB

More Complex Food Web

HOMEWORK TEXT PAGE 39 QUESTIONS: #1-6, 9,10