Climate Change - Climate Components, Heat Transfer, and Convection Currents

• Climate change and heat transfer can change our lives 
• Meteorology, energy and media are industries relate to climate change and heat transfer 

Earth’s climate system 

• What happens in one place affects the whole planet 

• Because of heat transfer 

Climate System and Climate Change 

• Climate system is the study of heat transfer 
• Climate is a pattern of temperature and precipitation for a region (over years)
• Weather is day-to-day variations 

The reason why Earth can sustain life 

• Solar energy 
• Atmosphere (air)
• The hydrosphere (water) 

Climate components 

Solar energy 

• The climate of the earth is determined by solar energy (the amount of energy coming from the sun)
• The amount of solar energy hitting the earth doesn’t change very quickly 

Atmosphere 

• A blanket of gas surrounding the Earth 
• It reaches up about 100km to the edge of space 
• The closest layer to the Earth’s surface is the troposphere 
• Mainly made up of 78% nitrogen and 21% of oxygen 
• The rest 1% has different gases that make up the atmosphere

• Argon 
• carbon dioxide

• Fewer particles of air as you go more up in the atmosphere

Hydrosphere 

• About 70% of the earth’s surface 
• Hydrosphere term references fo all the water in Earth’s system 
• Oceans 

• 97.5% of is salty 
• Make up a huge basin of water that holds a lot of heat
• Ocean absorbs hear and moves it around the globe in currents (determines the Earth’s climate)

• Freshwater 

• 2.5% of the hydrosphere 
• 70% of that is glaciers and icecaps and 30% is groundwater
• So only 0.3% is lakes and rivers 

Heat transfer radiation - transfers of energy 

• Earth is warmed up by solar energy 
• Tropical zones are closer to the sun than the poles are and get more solar energy and are more warmed up 
• The hear is moves around and it flows from the warmer area to the cooler ones 
• 3 ways to transfer heat

• Radiation 

• Transmission of energy 
• As this travels light from the sun takes the form of an electromagnetic wave (able to travel through outer space) 
• The electromagnetic wave deposit their radiant energy when they interact with some form of matter (air in the atmosphere, your skin or the Earth’s surface)
• Examples of electromagnetic waves

• Visible light
• Ultraviolet light
• Microwaves
• Radio waves
• X-rays 

• As shown in the diagram the difference between the types of electromagnetic waves is the length of the waves 
• As you move towards the right of the diagram the lengths of the waves get shorter and the radiation becomes more dangerous 

• Albedo 

• The amount of radiant energy is reflected by the surface 
• Any material absorbing radiant energy is called a heat sink 
• Different materials reflect and absorb different amounts of solar energy 
• Water has a higher albedo than land (water is more reflective than soil) 

• Oceans are good heat sinks because water can absorbs 5 times more energy than soil 

• Radiant energy can penetrate much deeper into the water than it can on land
• Larger bodies of water absorb a lot of energy with little change in temp.

• Conduction 

• Transfer of heat energy through the collisions of atoms in an object 
• Medium 

• The martial in which the energy is transferred

• Radiation doesn’t require a medium but conduction can’t take place without one
• For conduction to occur  the particles have to be in contact with each other
• Conduction if a slow process and is not responsible for most of the heat transfer around the globe 

• Convection 

• Transfer of heat energy in a fluid by actual movement of the fluid’s particles from one place to another (fluid can refer to liquid or gas)
• Particles vibrate but don’t move to another location
• The movement is from the different densities within the fluid 
• Ex. 

• If a pot of water is heated the water molecules at the bottom of the pot are heated (thermal energy) by conduction because they are in contact (with the bottom of the pot which is hot)
• As the water heats up the distance between the molecules expands and the water at the bottom becomes less dense
• Now that the water on the top is denser it will sink to the bottom pushing the warm water upwards 
• This circulating path of moving water is called a convection current as shown in the diagram as well

Convection currents

Convection currents 

• These currents are also present in our oceans and atmosphere because both are fluids and Earth is not evenly heated by the sun
• The area around the equator is warmer and than the polar regions because the sun strikes those areas more
• Currents transfer heat away from the equator and move it toward the colder poles 
• ocean currents carry warm waterfront the equator to the north and south polar regions 
• The Gulf Stream (a current) carries warm water from the Caribbean, north along and east coast of North America and then curves northeast towards England 
• Because of the Gulf Stream palm trees can grow in Southern England even though the latitude there is the same as in Winnepeg 

Local convection currents 

• The wind is the movement of air in the atmosphere as a result of convection currents 
• Some winds are local occurring only in relatively small regions 
• Land breezes or water breezes/sea breezes are examples of a local wind that can be formed on a warm day near a body of water such as a lake 
• Sea breeze cures during the day when the solar energy warms up the land faster than the nearby water 
• Resulting in the air above the land becoming warmer than the air above the water 

• The warm air rises faster over the land which causes the cooler denser air of the lake to flow towards the land 

• The direction of the wind reverses in the evening when land breeze forms 
• As the sun is setting the land cools faster than the water again because the water is a better heat sink 
• Now that the air above the water is warmer than the air above the land and a convection current form going from the land towards the water 

An example of a local convection current that occurs during the day is called thermal/thermal updraft, on a sunny day over land areas some parts get hotter than others, because they have a lower albedo 

• The upward drafts are often strong enough to allow large birds like vultures and hawks to soar upwards in circles for hours. 

• They use thermals as elevators, saving energy by gaining altitude without having to flap their wings
• Glider pilots also hunt for thermals to gain altitude