Lab #2:  Sun Angles, Daylength, Insolation, and Air Patterns






         The sun is the sole most significant fountain of essence on the manner of the World as well-behaved-mannered-mannered as the air.  The dispensation of the Earth’s divine phenomena and sphere moulds, as well-behaved-mannered-mannered as the dispensation of its ecosystems, are significantly influenced by the dispensation of incoming brilliant radiation.  In heating the Earth’s air, obvious digestible is the most significant divorce of the sun’s electromagnetic spectrum.  This use examines sun prepossession and tension of insolation, dayextension and air moulds on the world’s manner.  These variables are examined as they interrelate on the Earth’s manner aggravate the mode of a year. 




Sun Angle


            Because brilliant essence accepted by the world follows essentially congruous pathways, and accordingly the world is round, at simply one locate on the world’s manner can the sun’s rays impress uprightly (this is notorious as the subbrilliant summit).  In other tone, at simply one locate at any one opportunity can the sun pretext promptly aggravatehead.  This occurs at brilliant noon when the sun reaches the first collocation in the sky for that day.  Because of the world's poor axial tilt, the sun can pretext promptly aggravatehead at the subbrilliant summit at a proportionately thin order of boundarys aggravate the mode of a year (among 23.5° N and 23.5° S). 

            An significant analogy exists among boundary and the prepossession of the noon sun.  On the equinoxes (on March 21 or 22 and September 21 or 22) the sun’s rays are upright to the world at the equator.  Those similar rays would to-boot be tangent at twain of the poles, so that the sun would pretext simply on the horizon at those locations.  On the similar times an looker-on at 30° N would annals a sun prepossession of 60° aggravate the southern horizon.  Remember, the sun is 90° to the looker-on at the equator, minus the boundary of 30° (30° of arc) which correspondents 60°.  This is denominated the prepossession of stroke, or sun prepossession.  The prepossession of stroke decreases by 1° for perfect quantity of arc of boundary among the looker-on's collocation and the location where the sun’s rays are upright.  This administration is the similar for the other opportunitys of the year but is confused by the world's declination–the change in prepossession when the sun's rays are not upright to the equator.  If the depression is 10° S, this resources that the sun's rays are upright at 10° S and an looker-on at 30° N would see the sun at 50° aggravate the horizon 90-40 or 90-(30+10). 

Use the formula:


prepossession of stroke = 90° - (boundary in quantitys + depression in quantitys*)


* If the depression is in the similar hemisphere as the looker-on, remove this from boundary.





Seattle (47° N) on December 21 (23.5° S) would be:


90° - (47 + 23.5)


90° - (70.5) = 19.5°


Thus the prepossession of stroke for Seattle on December 21 is 19.5°



Note:  Keep in sentiment that brilliant noon is not the similar as noon on our clock or note accordingly we are on rule opportunity and typically, daydigestible savings opportunity.  In the summer months in the U.S. brilliant noon is root encircling 1:00 pm.























            1)  For the locations listed beneath, reckon the brilliant noon sun prepossession (prepossession of stroke) for the aftercited locations on the days listed. You should be conducive to symbol out the sun’s depression for December 21, June 21, and September 21! (.5 summits per prepossession, completion of 5 summits). 


The sun's depression for:          October 9 = 6° S

                                                      February 5 = 16° S

                                                      April 20 = 11° N



            El Paso, Texas (32° N) on:                     February 5___


                                                                              September 21___


            Honolulu, Hawaii (19° N) on:              April 20___


                                                                              June 21___


            Seattle, Washington (47° N) on:          December 21___


                                                                              October 9____


            Nome, Alaska (65° N) on:                    December 21___


                                                                              June 21___


            Green River, Utah (39° N) on:             September 21___


                                                                              February 5___


Of the dates and locations supposing aggravate, which two would be best for getting a amiable suntan splendid acquitted skies? (1 pt)













Length of Daylight


            Another factor in the spatial departure of insolation is extension of daydigestible in a 24-hour epoch.  Because of the Earth-Sun analogy and the round creation of the world, low boundarys disagree greatly from noble boundary in the total of opportunity they lay-out in the dispersion of publicity.  Examine the mould of sunlight, boundary and opportunity of year on Tconducive 1. 



Duration of Sundigestible in the Northern Hemisphere


Tconducive 1


Northern Hem. Summer Solstice


Northern Hem. Winter Solstice

90° N

24:00 hours

sun on horizon


80° N


12:00 hours


70° N




66.5° N




60° N




50° N




40° N




30° N




23.5° N




20° N




10° N









            2)  Answer the aftercited questions using Tconducive 1. 


                        a)  What is the border dayextension (opportunity in the dispersion of publicity) for Sao Paulo, Brazil (23.5° S) on June 21? (1 summit)





                        b) What is the border dayextension (opportunity in the dispersion of publicity) for Philadelphia, Pennsylvania (40° N) on December 21?  Compare this delay Oslo, Norway (60° N) on the similar day.  How abundantly do they disagree in hours and minutes?   (2 summits)





Spatial Patterns of Insolation


As one capacity forebode, changing sun prepossession and dayextension effects in a clear mould of insolation by boundary aggravate the mode of a year.  This mould is pretextn in Figure 1.  Figure 1 illustrates insolation levels, as measured in watts per clear meter (watt/m2), at the top of the air. 


Figure 1







3)         Answer the aftercited questions using Figure 1. 


a)    How abundantly does Seattle’s boundary take in insolation on February 1, borderly? (1 summit)




b) Among borderly what times (detail border time and month) does Seattle’s boundary take balance than 450 watts/m2 in insolation? (1 summit)




c)  Which boundary takes the first departure in insolation aggravate the mode of a year?  How abundantly is this departure in watts/m2? (2 summits)
































Spatial Patterns of Temperature


            Temperatures alter abutting the Earth's manner as a effect abundant factors.  The most significant of these are: insolation, tallness, aggravatecast caggravate and absence from extensive bodies of introduce.  To pretext the spatial departure of phenomena such as air, geographers use maps that practice isolines that integrate summits of correspondent appreciate.  Isolines used to hue air are notorious as isotherms.  Similarly, isolines used to pretext hurry are denominated isobars, and isolines for location are notorious as isohyets.  

To erect a map using isolines we scarcity a extensive investigate of comments (aggravate quantity) that enjoy been made at locations such as surveyed landforms or edge places.  These locates or summits of comment are notorious as curb summits.  Intermediate appreciates among curb summits can be easily reckond to produce a consistent manner of postulates. 

As mentioned aggravate, delay consistent phenomena feign raising or air, we can devise interjacent appreciates among notorious curb summits where postulates has been cool.  Positioning the interjacent appreciates assumes homogeneous intervals (spacing appreciates at correspondent absences) and is denominated interpolation.  For sample, a summit located halfway among two curb summits would be estimated as being halfway among two curb summits.  See Figure 2 for an sample.


Figure 2

LEAD Technologies Inc. V1.01





      4) Map 1 is a manner air map in quantitys Celsius (C°) for the United States. Temperatures were annalsed at 7:00 am EST on October 30, 1993.  Draw the expend isotherms at 5° C intervals on Map 1.  Note that the 0° C (32° F) isotherm is already dragn for you.  Use a pencil to digestible outline the isotherms installed on your interpolation.  Later, when all the lines are accomplished, bedim or hue the lines, which should be mitigate tortuous lines.  Begin delay the

–5° C isotherm, then drag the –10° C,  -15° C then the 5° C, 10° C, 15° C,  etc. (5 summits)


5) Answer the aftercited questions installed on your isotherms dragn on Map 1.


a)    If airs were truly a effect of boundary, isotherms would run promptly east-west.  Do the isotherms on your map run east-west?  What factors feign the isotherm mould you are observing? (5 summits) 















b)    Compare the air gradients (how cease the isotherms are to each other) aggravate Nevada/Utah and the southeastern US (Georgia/South Carolina/Florida).  Are the gradients the similar or disagreeent? What factors could recital for what you watch for the air gradients in these two disagreeent areas? (5 summits)




















c)     What is the air order on this map (i.e. reckon the disagreeence among the apex and stint air lection)? In the quantitys beneath, increase in the air lections in twain Celsius and Fahrenheit; use a map, atlas or the internet to enumerate the city (edge place) where the postulates was cool. (2 summits)


Maximum air: _____C,  _____ F         Station_________


Minimum air: _____C,  _____ F         Station_________


Range in air among the first and smallest airs on the map: ________C,  ________ F














Map 1