ATMO 336 1st Edition Lecture 29 Outline of Last Lecture II. Observed temp changes since 1850III. Implications of temp changes since 1850I. Global warming discussion Outline of Current Lecture IV. Climate introductiona. Strongest influencing factos= latitude and solar energy receivedV. Seasons (astronomical)a. Changes in intensity of sunshine receivedb. Changes in daylight lengthc. Earths orbit and axis of rotationd. EquinoxesVI. Intensity of sunshine- solar angle at noona. Depends on latitudeb. Solar declinationc. TropicsVII. Length of dayCurrent Lecture- Climate introductiono Strongest influencing factor on clime is the yearly variation in the amount of solar energy received from the sun This varies with latitude and time of year giving rise to what are termed “seasonal changes” Severity of seasonal changes depends on what latitude you live at Small seasonal changes at lower latitudes, stronger at higher latitudes- Seasons (astronomical)o Two seasonal changes that take place every year: Changes in intensity of sunshine received Changes I length of daylight hourso Largest seasonal changes occur at the north and south poleso Based on earths orbit and axis of rotation Elliptic plane= trace of the path that earth orbits the sunThese 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. Axis of rotation= imaginary line which extends through the earths north and south poles (one rotation every 24 hours) current axis is 23.5 degrees away fromperpendicular Seasons occur because the axis of rotation is not perpendicular to the elliptic plane since this causes the distribution of solar energy around the globe to change during the yearo On both vernal (spring) and autumnal (fall) equinoxes, the earth is not tilted toward or wary from the sun, the sun then shines directly on the equator and both hemispheres receive equal sunshine- Intensity of sunshine—solar angle at noono Since earth is a sphere, there is only one point on earth where the suns rays are striking perpendicular to the surface (sun is straight up in the sky) When sun is straight up, sun angle is 0 degrees When sun on the horizon, sun angle is 90 degrees Energy most intense where It hits perpendicular to the surface and sun angle is 0 degreeso Solar noon= exact middle of the daylight period or when the sun in halfway between sunrise and sunset (sun aligned with true north and south) This does not have to occur at 12pm!!! Though it is usually closeo Solar declination (or sub- solar point)= defined as the latitude at which the sun is directlyoverhead at solar noon) Found at only one latitude a day Changes slowly from day to day,  ranges from 23.5 degrees N latitude (tropic of cancer) on the summer solstice, happens around june 21st 23.5 degrees S latitude (tropic of Capricorn) on the winter solstice, happens around December 21st tropics= between 23.5 N latitude and 23.5 S latitude spring equinox happens around march 21st  fall equinox happens around September 231sto question: how many days per year is the noon time solar angle zero in Tucson (32 degrees N latitude)= 0, tucson is not located in the tropicso questions how many days per year is the noon time solar angle 0 degrees for a city located at 10 degrees latitude (Liberia)= 2 days. This is the same answer for anywhere in the tropics except right on the tropics of cancer or Capricorn where the noon-time angle is ) degrees for only one day (solstice days)o northern hemisphere, outside of tropics (north of 23.5 N latitude) non time sun is most intense (smallest sun angle) on the summer solstice. Least intense in the wintero solar angle at noon is simply EQUAL to the number of degrees of latitude between your latitude (your position on earth) and the latitude of the solar declination ex: what is the noon time solar angle in Tucson (latitude= 32 degrees N) on the following three date:- summer solstice= 8.5 degrees toward south- spring equinox= 32 degrees toward the south- winter solstice= 55.5 degrees toward the north- length of dayo more hours of daylight= more time for sun to heat earth’s surfaceo the seasonal (yearly) changes in length of daylight hours are smallest at the equator and get larger toward the north and south poleso march 21st (spring or vernal equinox) and September 21st (fall or autumnale equinox), every latitude on earth has exactly 12 hours of sunshine and 12 hours of darkness (then is when axis of rotation does not point at all toward or away from the sun) equinox= means equal day and nighto acrtic and antarctic regions= between 6.5 degrees and 90 degrees latitude where there is at least one day with 24 hours of sunshine and one day with 24 hours of darkness eachyear- seasons (popular usage)o summer solstice is not typically the warmest time of the year in northern hemisphere, warmest temps generally occur near the end of july and the beginnig of august, even though the max heating from the sun happens on the summer solstice ( around june 21st)= lag between max solar heating and max temps oceans have large thermal interia where temp changes are slow in response to changes in radiational heating and cooling (max heated ocean temp usually in september)o also a lag between max heating at solar noon and time of day with highest temp (2:30-4pm)EXAMPLE: For Tucson, compare the differences in solar heating, average temperature, and trends in average temperature on the Spring Equinox (March 21) with the Fall Equinox (September 21).o ANSWER: The solar heating is the same on both dates. The solar declination is located at the equator on both dates, so the solar angle at noon in Tucson is 32° south of straight up. In addition, there are 12 hours of daylight on each date. The average temperature is much warmer on Sept 21 compared with Mar 21 because Sept 21 is much closer to the time of highest temperatures (end of July / beginningof August) than Mar 21. (For Tucson ave high is 74°F on Mar 21 and 93°F on Sept 21.) The trend on Mar 21 is for increasing temperatures as time moves forward (from the lowest temperature of the year (end of Jan) to the highest (end of July)). The trend on Sept 21 is for decreasing temperatures as time moves forward (from highest at end of July to lowest at end of