KEEPING WARM 
Left: The cup-shaped blossoms of 
the pasqueflower collect the 
warmth of the sun. On a sunny 
morning in early spring, temperatures 
inside the flowers can be as much 
as 18 degrees Fahrenheit 
warmer than the surrounding air. 
Rick Furmss. AlaskaPhoto 
Below: Poppies in Alaska follow the 
sun with their highly reflective 
petals. The heat stored by the 
flowers’ stamens and carpels may 
accelerate the development of 
pollen and seeds. 
Nancy Simmerman. AlaskaPhoto 
that we can detect only by nonvisual 
means. Ultraviolet wavelengths are 
shorter than those of blue light and 
energetic enough to damage living 
things exposed to them. Fortunately for 
life on earth, most of the potentially 
harmful ultraviolet rays are filtered out 
by a high-altitude layer of ozone. Bees 
can see some ultraviolet colors that are 
invisible to us, and some flowers have 
ultraviolet patterns that are important in 
pollination, relationships. 
At the other edge of the rainbow, red 
fades into the long infrared (IR) wave- 
lengths, which we do not see but can feel 
as heat. Almost half of the total solar 
energy reaching the surface of the earth 
is in the IR wavelengths. This energy 
heats all exposed surfaces, evaporating 
water and warming plants and animals; 
although abundantly available to plants, 
it is not used in photosynthesis. The 
shorter IR wavelengths are the most 
energy rich and are received primarily 
from the sun; longer IR wavelengths, 
associated with radiant heat of lower 
temperatures, are radiated from all 
heated surfaces and are absorbed by 
nearly all surfaces. A room will feel cold 
to us if we radiate more heat to the walls 
than we receive from them. 
Much of what is understood about the 
complex energy environment of plants 
and animals is due to the work of bio- 
physicist David Gates and his col- 
leagues, who have carefully measured 
and calculated the amounts of energy of 
all sorts that enter and leave the earth’s 
