ATMS 120 1st Edition Lecture 2 Outline of Last Lecture I Overview of the atmosphere II Composition of the atmosphere and keeping the Earth warm III Temperature IV The relationship between temperature and density Outline of Current Lecture I General temperature variations II Seasonal variations in temperatures III Seasons the effects of latitude IV Proximity to large bodies of water V Vertical temperature variations Current Lecture I Uneven surface heating drives atmospheric circulations The two primary causes of this are 1 The angle of the sun s rays and length of day light hours are not constant This is what causes seasons 2 The earth is covered with many different surface types that absorb energy differently Example a desert surface type vs a mountainous surface type The Sahara Desert and the Himalayan Mountains are at the same latitude but experience very different temperatures The average surface air temperature in the world is 59 degrees Fahrenheit 15 degrees Celsius with a range between 129 degrees Fahrenheit and 134 degrees Fahrenheit They key idea is that mothernature constantly tries to get to equilibrium II Summer Solstice June 21st The sun s rays are direct on the Tropic of Cancer 23 5 degrees North Most daylight hours occurs during this time Autumnal Equinox September 21st The sun s rays are direct on the equator There are 12 hours of daylight and 12 hours of night Winter Solstice December 21st The sun s rays are direct on the Tropic of Capricorn 23 5 degrees South These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute The least amount of daylight hours occur during this time Vernal Equinox March 21st The sun s rays are direct on the equator There are 12 hours of daylight and 12 hours of night The tilt of the earth on its axis causes the sun s rays to become more or less direct which concentrates or disperses the sun s energy throughout the year The distance between the sun and the earth doesn t have any effect on temperature III The greater the latitude the greater the yearly variation in temperature During the winter there is a low sun angle fewer daylight hours and the sun s path through the atmosphere is long During the summer there is a high sun angle more daylight hours and the sun s path through the atmosphere is short Example A town in Sudan is at 12 degrees N in latitude Its average temperature in January is 85 and 105 in July a difference of 20 degrees A town in Illinois USA is at 40 degrees N in latitude Its average temperature in January is 32 and 85 in July a difference of 53 degrees A town in Northern Russia is at 66 degrees N in latitude Its average temperature in January is 43 and 72 in July a difference of 115 degrees Therefore greater latitude results in greater variation in temperature IV The average temperatures in San Francisco is generally the same throughout the year whereas temperatures differ throughout the year in places like Urbana Illinois and Dover Delaware even though all three cities are at around the same latitude The reason San Francisco doesn t fluctuate much in temperature throughout the year is because land heats and cools five times faster than water does combined with the fact that weather in the United States comes from the west The Pacific Ocean takes longer to change temperatures and this affects cities immediately east of it keeping them relatively constant V The layers of the atmosphere include the Troposphere Stratosphere Mesosphere and Thermosphere We live in the Troposphere which is also where all of the world s weather occurs 80 of the atmospheric mass is in the troposphere The layers of the atmosphere are defined by their temperature profile