Now an entirely
new topic. You'll find a link to an Optional Assignment at the end of
these notes.
How would you describe Tucson's climate? Hot and
dry?
You're basically conveying information about temperature and
precipitation. Here we'll just concern ourselves with
temperature. It does get pretty hot in Tucson in the
summer. But it doesn't stay hot all year. With just two
numbers, (i) the annual mean or annual average temperature and (ii) the
annual
range of temperature you can give someone a pretty complete idea of the
temperature in Tucson and how it changes during the year. More
detailed statistics for Tucson are available at this Tucson
climate data
link.
There are three or four main factors that determine a region's annual
mean and annual temperature range.
Latitude affects both the annual mean and the annual range of
temperature. The polar regions have colder annual average
temperatures than any other location on earth. As we'll see, some
of the other
controls of temperature work together with high latitude to make
Antarctica and the South Pole colder than the North Pole. The
hottest regions on earth are found near 30 latitude, not at the Equator
(you'll find some discussion of this on pps. 79 and 80 in the
photocopied ClassNotes which wasn't discussed in
class)
The annual range of temperature increases with increasing
latitude. There is little or no seasonal change at the Equator.
Water has a higher specific heat, it takes more energy
to warm a gram of water than to warm a gram of soil.
Additionally, some of the
incoming energy is
used to evaporate rather than warm water. Incoming sunlight
penetrates into a body of water and is used to warm a larger
mass of water. These three factors mean that water will warm more
slowly and won't get as hot during the summer as land. If you've
ever been to the beach in the summer you probably remember that
the sand on the beach gets much hotter during the day than the ocean
water.
The table below summarizes the three controls of
temperature that we
have covered so far. One of them affects both the annual mean and
annual range, one affects just the mean, and the other just the annual
range.
One final factor:
Cities on the west coast and east coast of the US can
have very
different climates even if they are at the same latitude and
altitude. A cold southward flowing ocean current is found along
the West
Coast. The warm Gulf Stream current flows northward along the
East Coast. Winds at middle latitudes generally blow from west to
east. The city on the West Coast will feel the full moderating
effect of the ocean. The city on the East Coast will be affected
by the Atlantic Ocean but also by winds blowing across the interior of
the US.
This is the end of the required reading. What follows is
supplemental reading.
What kind of climate would you expect to find at Point X, on the map above, near the
Equator
in the middle of
the Pacific Ocean?
We'll answer that question but first you must hear about an awesome
field
experiment that I took part in several years
ago. What is the tie in with this class? A good part of the
experiment was conducted at a relatively small island near the equator
in the middle of the Pacific Ocean. Now that we have just learned
about some of the factors that control/determine a region's climate you
should understand that
there is very little change from summer to winter in regions like this.
I think you'll be surprised how little change there sometimes can be.
The photograph above appeared on the cover of the April 1994
issue of
the Bulletin of the American Meteorological Society. If you look
closely you might recognize one of the two bald men in the photo.
This photo was taken on
Kapingamarangi
Atoll (shown on the map below, see pps 81 & 82 in the photocopied
ClassNotes), shortly before part of the research team was to board ship
and leave Kapingamarangi. The remaining group members were going
to remain behind and operate
all of the research equipment.
What we were doing on Kapingamarangi? We were a small
part of a much larger field experiment. Our job
was to install the tall white lightning detector at the left edge of
the photograph. We would later travel to Rabaul (on New Britain
island) and Kavieng (New Ireland island) in Papua New Guinea and
install
two more detectors. Papua New Guinea would turn out to be a very
different place. Until recently some of the highland tribes there
practiced cannibalism and shrunk heads. You can also get
some very nasty strains of malaria in Papua
New
Guinea.
To get to Kapingamarangi you first need to fly to Pohnpei (an
island in
the Federated States of Micronesia). The route is shown
above. Then you take a cargo ship for about a 4 day sail to
Kapingamarangi. We had intended to fly to Pohnpei, set sail for
Kapinga the next day, and then spend about a month on
Kapingamarangi. The ship however was delayed 3 weeks. That
gave us plenty of time to visit the island of Pohnpei but ultimately
meant we could only spend a few days on Kapingamarangi. Here's a picture
of
the
airport at Pohnpei. Note the runway runs from one edge
of a small island to the opposite edge.
Pohnpei is a fairly large island and, together with some of
the
other Micronesian islands, is a popular, world-class, snorkeling and
scuba
diving destination. Here's a picture
of Kolonia (the airport is at the left end of the causeway in the
photo), the largest town on Pohnpei. Kolonia has a weather
station that
is
operated by the US National Atmospheric and Oceanic Administration
(NOAA).
Pohnpei
is located at low latitude in the middle of the Pacific
Ocean. Both of those factors will reduce the annual range of
temperature. How
large
do
you think the annual range is?
The following precipitation data show that Pohnpei is also one of
the
rainiest locations on earth
Close to 400 inches of rain may fall in the interior of
Pohnpei. The rainiest location on earth is in Hawaii with about
460 inches of
rain per year.
Pigs
are also an important part of daily life on Pohnpei, Kapingamarangi,
and the other islands in Micronesia.
After we had finished our work in Micronesia and had traveled to
Papua New Guinea, I began collecting carved wooden pigs from some of
the local carvers.
The Micro Glory (shown below) sails back and forth between
Pohnpei
and Kapingamarangi about once a month. The ship carries supplies
to the people on Kapingamarangi and some other small islands.
They pay for the supplies with
pigs (the pigs are sold on Pohnpei). We shared deck space on the
Micro Glory on the trip back to Pohnpei with 20 to 30 pigs (they were
hoisted aboard in nets)
Most of the lower deck in the photo above (under the
hoists)
was occupied by pigs on the return trip. One of the pigs died on
the return trip - that was a very serious matter.
We also had a chance to sample some of the local beverages.
Drinking sakau (as it is called on Pohnpei) turns your mouth and
throat numb. It is supposed to relax you, make you sleep more
fully, and doesn't seem to have any after effects. Until fairly
recently
you could buy kava in pill form at local supermarkets. However,
because of reports that it can cause serious liver problems, that is no
longer the case. There are no reports of liver problems when
drinking kava that has been prepared in the traditional way. Here is a link to a
Wikipedia article on kava.
We never tried betelnut. Areca nuts are wrapped in betel
leaves
and chewed together with lime (lime is pretty caustic, that is one of
the reasons I didn't try betelnut). The resulting mixture is a
mild
stimulant (some people add tobacco to the mix). The most
interesting aspect, however, is that chewing betelnut colors your mouth
and teeth
bright red.
You
don't
swallow
betelnut,
you
spit
it
out.
You
see the bright red stains
on sidewalks and the ground wherever you go. Most hotels will
also have a large sign near the entrance reminding guests not to chew
betelnut inside the hotel. You can read more about betelnut here.
During the spring semester I sometimes suggest you might consider
a trip to Pohnpei for Spring Break. The last time I checked a
roundtrip flight from Pheonix to
Pohnpei (by way of Honolulu, Guam, and Houston on the return flight)
wasrunning about $3400.
Here's the link to the Optional
Assignment
