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Ed Lu letter from space #5

25 Jun 2003

Watching the World Go By

Part 2 of 2

Southern Canada is covered with a myriad of small lakes. If the sun
is overhead, you can see the sun glint off the lakes, rivers, and
streams - briefly lighting them up as the reflection point moves
across the surface of the Earth with you. Looking left we pass Hudson
Bay. Even now in the summertime there is ice on parts of the bay. To
the right pass the Great Lakes. One thing that is surprisingly easy
to see from space is airplane contrails, the white condensation
trails left behind highflying jets. You can see the white lines
converging on Chicago from all directions. Continuing eastward, we
pass over the St. Lawrence River, over Newfoundland, and then out
over the Atlantic Ocean. The total time to cross North America has
been about 12 minutes. 

Over the North Atlantic Ocean lately there have been wide expanses of
clouds covering the ocean like a blanket. These large weather system
clouds look like a white 1970s era textured carpet with bumps and
ridges and the occasional thunderhead cloud popping up through. As we
head southeast towards the coast of Africa, you can see in the
distance the red deserts of the western Sahara. The color here is a
chalky red, almost like the color of red bricks. Lately there have
been large dust storms over the desert blurring out any detail on the
ground. We skim the coast heading southeast over the war-torn
countries of Sierra Leone and Liberia, and continue towards the Cape
of Good Hope at the southern tip of Africa. 

If Hawaii is in daylight, then this side of the Earth will be on the
night side. Since we orbit the Earth 16 times a day, we see 16
sunrises and sunsets each day. Looking backwards towards the horizon
you can see the sunset. Sunsets and sunrises are beautiful, with a
very thin distinct color layers in the atmosphere. They range from
orange and red near the surface to various distinct shades of blue,
purple, and finally black. The sun rises and sets fairly quickly at
the speed we are flying, taking just a few minutes for us to go from
dark to light or vice versa. Looking down on the ground you can see
the line dividing the day and night sides of the Earth. If there are
high clouds, you can often see the long shadows they cast when the
sun is low in the sky. 

At night, you can easily see city lights. Larger cities are very easy
to pick out, as well as sometimes the lights along major roads
between them. As we round the southern tip of Africa, you can see the
lights of Cape Town. City lights have a yellowish hue, which I think
is due to the fact that most streetlights are sodium vapor lamps
which have a yellowish tinge. We then head eastward over the southern
Indian Ocean. 

At night, the dominant thing you see when you look down is
thunderstorms. Lightning lights up the clouds in sometimes
spectacular displays. At any given time at night, especially over the
tropics, you can see one or more lightning storms going on. The
lightning flashes illuminate the clouds from within, and ripple
through the storm systems. I enjoy turning off all the lights in the
docking compartment, and watching thunderstorm systems at night
through its sideward facing windows. The southern Indian Ocean is a
great place to watch thunderstorms.

As we near Australia, if you look towards the horizon southward you
can see the aurora. The aurora look like glowing green curtains which
move upwards from the top of the atmosphere. The curtains intersect
the atmosphere in a curved line, which appears as a bright green line
south of Australia. There are times when we actually fly through the
aurora, and you can look downwards and see the green glow below you.
Sometimes there are traces of red along with the predominant green.
We've taken some time-lapse movies looking towards the horizon as we
fly past the aurora. 

The next part of this orbit takes us northeast across Australia. In
the daytime, you can see the bright red color of the deserts of
central Australia. At night, by the absence of lights you can see how
few people live in this area. To the right is the coastal city of
Sydney. The final part of this orbit crosses over the Great Barrier
Reef and various South Pacific islands on our way back towards the
equator. Most of the small islands dotting the South Pacific are
ringed by coral reefs. The most striking thing about these reefs and
small atolls is the bright almost iridescent aquamarine green color
of the water. And that takes us to the finish of this orbit - total
time around the world is 90 minutes. In a later installment I'll
write about some of my other favorite orbit tracks. I'm only
including a few pictures here so this e-mail isn't too huge. If you
want to see lots more pictures that we have taken, go to the
Expedition 7 Gallery or to the NASA Earth Observation Web Site where
you can find lots of interesting stuff.

-Ed Lu-

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