1. Energy From the Sun Chapter 15: The Atmosphere

2. Energy Transfer The Sun gives off lots of energy, and most of it reaches our atmosphere. The energy the Sun emits is transferred in 3 different ways: 1.Radiation: light and heat, transferred through electromagnetic waves. 2.Conduction: when a heated object transfers energy to molecules in the air, allowing them to move faster. 3.Convection: air moves due to density differences. Warm air rises, cool air sinks, moving warmer air to cooler areas. (best way to transfer energy in the atmosphere!)

3. What is Wind? Wind is the result of horizontal differences in air pressure. Air flows from areas of higher pressure to areas of lower pressure. Differences in air pressure are caused by uneven heating of the Earth's surface. Therefore, we can say that the Sun (solar energy) is the ultimate cause of wind. Winds do not blow directly north to south…why? Because of the Coriolis effect! Remember this is due to the rotation of the Earth. Look at the picture!

4. Answer the Questions about the Video ClipVideo Clip 1.The engine that powers our weather is the _Sun__. 2.Energy from the Sun gets _absorbed_ by the Earth and converted to _heat_. 3.True or False. At any given time, some places on Earth are heated more strongly than others. 4.Warmer air becomes _thinner_ and _lighter_, and _rises_. _Cool air moves in to take its place. This movement of heat through the fluid of air is known as _convection_. 5.Convection creates areas of _high_ pressure and low_ pressure, and gives us our _wind_. 6.Water __retains__ and __releases_ the heat from the Sun. 7.The differences in heat between the _land_ and _sea_ greatly influence local weather. 8.If you don’t like the weather, wait a minute and it will __change__.

5. Strong Winds At certain latitudes, air will rise or sink, depending on the amount of solar radiation received. This creates 3 main circulation cells: Hadley, Ferrell, and Polar. Within these convection cells, three global wind systems are found: 1.Tradewinds: where air rises at the equator and sinks at 30 0 N and S. 2.Westerlies: where air sinks at 30 0 N and S and rises again at 60 0 N and S. 3.Polar easterlies: where air rises at 60 0 N and S and sinks again at the poles.

6. Weak Winds Horse latitudes or Subtropical High are subtropical latitudes between 20 and 30 degrees both north and south. This region is an area of variable winds mixed with calm periods. Horse latitudes got its name from the Persians having to throw their horses overboard to lighten their load. This allowed them to travel faster when the winds weren’t blowing! The Intertropical Convergence Zone (ITCZ), also known as the doldrums, is a belt of low pressure around Earth at the equator. Early sailors named this belt of calm the doldrums because of the inactivity and stagnation they found themselves in after days of no wind.

7. Daily Winds Land and sea breezes are created due to the heating differences of land and water. Is especially noticeable along coastlines. Sea-breezes occur most often in mid-summer during daylight hours when there is a large difference between the temperature of the air over the land and the temperature of the air over the still cold sea. At night, the land cools off quicker than the ocean due to differences in their specific heat values, which forces the dying of the daytime sea breeze. This results in a land breeze.