Why does the sky change its color during a sunset?
                     Why does the sky 
change its color 
during a sunset?
INTRODUCTION
 The colors we see in  the sky come from sunl ight  that  
i s  scattered by molecules  in the  atmosphere .  This  
process  is  cal led Rayle igh scatter ing.
Source: scied.ucar.edu
SEPARATE 
WAVELENGTHS
 Nitrogen and oxygen make up most of  the molecules  
in our atmosphere,  but  any gas or  aeroso l  suspended 
in the ai r  wi l l  scatter  rays  of  sunl ight  into separate  
wave lengths of  l ight .  
Source: scied.ucar.edu
Why Is the Sky Blue?
 Sunl ight  is  made up of  a l l  the colors  of  l ight .  I t  
appears  as  whi te  l ight  when al l  the colors are  
together.  Sunl ight  t ravels  as waves of  energy,  and 
diff erent  co lors of  l ight  have diff erent  wavelengths.
Source: scied.ucar.edu
How Does a Rainbow 
Form?
 Rainbows resul t  f rom l ight  that  scatters  ins ide of  
water  droplets .  
 This  is  why you only  see ra inbows after  i t  has  ra ined,  
when there  is  water  in  the atmosphere and the Sun is  
sh in ing.
Source: scied.ucar.edu
Why Are Sunrise and 
Sunset so Colorful?
 The angle of  sunl ight  as  i t  enters the atmosphere  
also aff ects the  color  of  the  sky.  
 During sunr ise  or  sunset ,  when the  Sun is  c lose to  
the  hor izon,  the  l ight  must  t ravel  through more of  
the  atmosphere  than i t  does when the  Sun is  
overhead.  
Source: scied.ucar.edu
How Does Air Pollution 
Affect Sunset Colors?
 Intense red sunsets are often v is ible  when forest  
fi res are  burning nearby,  or  when volcanic  erupt ions  
happen.  
 The most  heavi ly  pol luted c i t ies  in the  wor ld a lso  
tend to have more orange and red sunsets,  resul t ing 
f rom an abundance of  human-made aerosols .
Source: scied.ucar.edu
Why does a setting sun 
look orange?
 When the sun sets,  i ts  l ight  i sn 't  just  graz ing the  
Earth,  as seen from where you are,  but i t 's  a lso  
coming through a lot  of  Earth's  atmosphere .  
 That  means a lot  of  molecules  and smal l  part ic les  in  
the  ai r ,  which change the  d irect ion of  l ight  rays.  
Source: scied.ucar.edu
When the sun look red?
 Because red has the longest  wavelength of  any 
v is ib le  l ight ,  the sun is  red when i t ’ s  on the  hor izon,  
where  i ts  extremely long path through the  
atmosphere  b locks  a l l  other  colors .
Source: scied.ucar.edu
THANK 
YOU