Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Introduction To Weather Dynamics What do you know about weather? • • • • Key terms? Why is it important? How does it affect us? How does it affect other animals/plants? Meteorology The study of the Earth’s atmosphere and weather systems. Weather The day to day changes in the atmosphere at a particular location on Earth. Climate A widespread, long-lasting and recurring conditions of the atmosphere. Atmosphere The layer of gases that surrounds planet Earth. The gases are held in place by gravity. Heat and Temperature • To understand weather and climate we must understand temperature and heat! • What happens when you hold a chocolate bar in your hand? • THIS IS NOT PART OF THE JOURNAL… Different ways that heat “moves” • There are 10 pictures • For each picture determine the following answers: • A) What makes you think that heat is moving; is there any evidence that you see showing heat transfer? • B) Where does the heat come from and where does it go? 1. Your breath on a cold day 2. Hot chocolate 3. Hot soup in a bowl 4. Geysers in Iceland This whole area is a geothermal park sitting on top of a huge, boiling cauldron. Steam and gas escape from the geothermal system. There are hot springs and mud pots. Mud pots are often around 70-80’C. 5. Chicks are happy in the winter until their heat lamp 6. The Desert – heat waves create a mirage 7. Baking and Cooking 8. Melting Ice Cream 9. Fireplace 10. Boiling Water Heat can be transferred in three ways: 1. Conduction 2. Convection 3. Radiation 1. Conduction – the easy definition Heat is transferred through a material without the material moving. Only the energy moves. 1. Conduction - complicated Heat is transferred from one object to another. As one molecule is heated it begins to move and shake rapidly. It passes some of its heat energy to other molecules around it. All the molecules of an object pass heat from one to another, until they are all hot. • http://www.scool.co.uk/gcse/physics/energytransfers/revise-it/how-does-heat-energymove Conductors • Solids are the best conductors • Solids have atoms that are closer together so the heat is transferred easier. • In gases especially the atoms are too far apart. Conductors • Metals are the best conductors. • Example: Frying pan • Example: The expansion joint on a bridge • Gases are the worst conductors. • Example: Air • http://www.wisconline.com/Objects/ViewObject.aspx?ID=SCE304 2. Convection – easy defintion Transfer of heat energy through moving liquids or gases. Convection Hot air rises in cold air. Hot liquid rises in cold liquid. 2. Convection Highly energetic atoms or molecules move from one place to another. • When a liquid or gas heats up, the particles move around more. • This makes the particles spread out, so they have more room to move. • This lowers the density of the substance. The hotter it gets, the lower the density goes. • It is this lower density that makes the hotter substance rise. The cooler substance has a higher density, which makes it sink. Example of Convection • The heat in a boiling pot of water (steam) • The heat in a room that rises to the top of the room • http://www.wisconline.com/Objects/ViewObject.aspx?ID=S CE304 3. Radiation Atoms or molecules emit electromagnetic waves. These waves carry energy through space and deposit it only when they interact with some form of matter. Examples: Toasters Sun’s energy (in the air) that makes us hotter Radiation and Colours • What colours are the best at radiation? – Black and dull colours These colours absorb and emit heat. Poor radiation colours: White and shiny colours. These colours reflect heat. Keeping the Heat • Where is heat lost the most? • Why? • Heat energy is transferred from homes by conduction through the walls, floor, roof and windows. It is also transferred from homes by convection. For example, cold air can enter the house through gaps in doors and windows, and convection currents can transfer heat energy in the loft to the roof tiles. Heat energy also leaves the house by radiation through the walls, roof and windows. • http://www.bbc.co.uk/schools/gcsebitesize/s cience/aqa/energy/heatact.shtml • Now let’s go back to those pictures and determine what type of heat transfer is occurring! 1. Your breath on a cold day 2. Hot chocolate 3. Hot soup in a bowl 4. Geysers in Iceland This whole area is a geothermal park sitting on top of a huge, boiling cauldron. Steam and gas escape from the geothermal system. There are hot springs and mud pots. Mud pots are often around 70-80’C. 5. Chicks are happy in the winter until their heat lamp 6. The Desert – heat waves create a mirage 7. Baking and Cooking 8. Melting Ice Cream 9. Fireplace 10. Boiling Water Quiz • 1. What substances can convection happen in? – In solids and gases In solids and liquids In liquids and gases • 2. What type of radiation do all hot objects emit? – Infra-red radiation Microwave radiation Gamma radiation • 3. What are the best absorbers of thermal radiation? – Light, dull surfaces Black, shiny surfaces Black, dull surfaces • 4. What are the worst emitters of thermal radiation? – Light, shiny surfaces Light, dull surfaces Black, dull surfaces • 5. How does heat pass through a single pane of window glass? – By conduction and convection By conduction and radiation By convection and radiation