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Introduction: The Earth Revolutions and rotation Earth is approximately 91 – 95

Introduction: The Earth Revolutions and rotation Earth is approximately 91 – 95 million miles away from the sun Plane of the Elliptic – the imaginary flat surface on which the earth orbits. Earth spins on an axis that is tilted 66.5 degrees, but the tilt is constant For the Northern Hemisphere: Summer Solstice is June 22, the date where the North Pole is closest to the sun and Winter Solstice is December 22, the date where the south pole is closest to the sun When the earth is closer to the sun the climate is warmer, and when it is further away, it is colder. Solar radiation is made up of the direct EM waves (99% of energy) Due to the tilt, the day is longer in the north hemisphere in the summer and longer in the winter and this is more prominent as the you go more and more north. At 22.5 degrees north + south are the tropics, north  cancer and south  Capricorn, (Tip: remember alphabetical order, cancer is before Capricorn) At 66.5 degrees north + south are the circles, north  arctic circle and south  Antarctic circle and this area during the solstices are 24 hour sun Modern scientific revolution started with astrophysics Time = human observation of regular motion In the middle of the solstices are equal days and nights (12 +12) these are called the equinox‘s (autumnal and vernal  autumn and spring) Time was regularized after the trains were introduced, 1847 the railroads got together and decided to use GMT and time zones are approx 15 We determined the time through tracking the sun‘s position at the solstices. Our ancestors observed the apparent changes in the position of the sun and drew from these observations some astute and for their time remarkably accurate conclusions i.e. by tracking the position the sun was in the sky (high or low) they were able to determine the 4 divisions of the year. By 4000 BCE, the Egyptians had calculated the length of the year to be equal to 365 days, and a couple of millennia later, their successors had sharpened the number to 365 1/4 days. The natural division of the day between sunlight and darkness was not good enough. To measure smaller units of time required artificial inventions that would produce regular brief movements, which could be used to "count" the passage from one "time" to the next. Hourglass and Water Clock were both formed on the idea of a steady flow of a substance and the level left in the vessel allows us to determine the time. Escapement is a gear, which converts vertical pressure into circular motion Longitude (meridians) – meet at the poles, prime meridian is the GMT line Latitude (parallels) – equator is 0, north is x degrees north, and south is x degrees south. The International Meridian Conference, held in Washington, DC in 1884, selected the line running through the Royal Observatory in Greenwich, England as the "Prime Meridian," or zero degrees longitude, which has since gained universal acceptance. Time Zones were created on the premise that everyone would get about 12 hours of day and 12 hours of night (24 hours in a day was decided by consensus) – about 6 AM to 6 PM. Therefore to make some sort of uniformity throughout the world, the decision was made to divide the world into 24 time zones to correspond with the number of hours in a day. Therefore the sun rises in the east and the earth essentially rotates through the ‗sunrise‘ until it rises in the west (Tokyo vs. San fransisco, for example). There is one exception to this rule: International Date Line is the point at which you turn back a day, approximately the other side of the earth to the Prime Meridian. If clock time became continuously later as one moved east, then after traveling through 24 time zones, a person would arrive back where he or she started with a clock that was 24 hours (or one day) later than it was at the start. Since it cannot be both Monday and Tuesday in the same place at the same time, the date must be reset to correct for this error. When moving east to west (Russia to Alaska) to take away a day, and add a day when travelling west to east. THE ATMOSPHERE -What is the atmosphere composed of? 78% Nitrogen (innate gas, doesn't affect very much) 21% Oxygen, 1% Trace Gases (includes Carbon Dioxide, Water Vapor, Methane, Nitrous Oxide) -How is the atmosphere heated? The Sun gives off short wave radiation, which hits the Earth that gives off long wave radiation that warms up the rest of the earth. This is evident when you look at mountains which are closer to the sun, yet are very cold. Things closer to the surface are the warmest. -Why is the Earth heated unevenly? The earth is heated unevenly because not all places on the Earth are heated evenly. If the area is far away from the sun (like the poles) then it is normally colder, unlike places that are closer to the sun (like the equator) that are warmer. -What are the characteristics of warm air? Cold air? Warm air absorbs moisture a lot more than cold air, and it is also very light. Cold air is heavier, more dense but does not hold as much air. When warm air gets colder, it releases a lot of water as rain (condensation) -How does the Hadley cycle work? Sun rays hit the Earth. At that point, the air where the ray hits the Earth gets warmer. That air rises. Colder air replaces it. As the warm air rises and moves away, it cools, falls and replaces warm air elsewhere. This cycle continues in a North-South motion continuously. -What does high/low pressure mean? This slide demonstrates the effects of "air pressure" or the difference between warm (light) and cold (heavy) air. The term "high pressure" means that air above this point is cold, or colder than the neighboring air, and cold air being heavy forces its way earthward. Conversely, "low pressure" means that air above this point is warm, or warmer than the neighboring air, and warm air being light rises. Cold, heavy air presses downward to form a center of high pressure, while warm, light air rises to form a center of low pressure. -What happens to moisture in the context of the Hadley cycle? If the Sun heats up air, then the air gets warm, and it picks up moisture, and then as it moves away from the earth surfaces as it rises then it releases the water as rain or snow. -What impact does the Hadley cycle have on global precipitation patterns? Where does it rain most? Least? Why? ( I essentially took this from one of the slides, it explained it really well) Warm air absorbs moisture, and when warm air is cooled, the water vapor condenses, or changes from the gas to the liquid phase. Thus, a column of light, warm air (a low pressure system) that rises and as it moves away from the earth grows cooler, is likely to cause the condensation of water vapor to produce rain. Look around the globe near the equator, and what do you see? Lots of rain, produced by lots of rising warm air -- and as a consequence, lots of rainforests. Conversely, cold air absorbs relatively little moisture, and when cold air is warmed, this causes the opposite effect, which is to evaporate whatever moisture is available in the surrounding environment, changing it from the liquid (water) to the gas (water vapor) phase. Thus, a column of cold, heavy air (a high pressure system) that sinks and as it nears the earth grows warmer, is likely to speed the evaporation of surface water. So, look around the globe near latitude 30 degrees N and S, home of the Subtropical Highs, and what do you see? Lots of dry weather, produced by lots of falling cold air -- and as a consequence, lots of deserts. -What effect does the Coriolis force have on global wind patterns? The Coriolis effect turns winds to the right (clockwise) in the Northern Hemisphere and to the left (counter-clockwise) in the Southern Hemisphere. -How were wind patterns important in the period of European exploration? They were important because they explained how Spain and Portugal were the first to go the New World, their position in Europe allowed them to be the closest to the Northeast Trade winds that blew them straight towards Central America and the Antilles. -How did Europeans sail around the Cape of Good Hope? Easily. They sailed as far south as they could then they caught the Westerlies that blew them around the Cape of Good Hope -Be familiar with the following: >short-wave radiation- what the Sun emits that hits the Earth; the Earth emits long wave radiation >Hadley cycle- North -South air uploads/Geographie/ map-guide.pdf