Notes
for the lecture on Monday 1/7
Definition of climate; distinction between
weather and climate. The
American Meteorological Society Glossary
of Meteorology defines it as
"the slowly varying aspects of the atmosphere-hydrosphere-land
surface system. It is typically characterized
in terms of suitable
averages of the climate system over periods
of a month or more,
taking into consideration the variability
in these time averaged
quantities. The glossary notes that
the concept of climate has
broadened and evolved in recent decades
in response to improved
understanding of the underlying processes
that determine climate and
its variability. The new idea is
that climate varies from one year
to the next, from one decade to the next,
from one century to the
next, etc. We used to think of climate
as having varied in the
distant past, but now, for all practical
purposes, being constant.
The 'climate system' is defined as the
system, consisting of the
atmosphere, hydrosphere, lithosphere and
biosphere, determining the
earth's climate as a result of the mutual
interactions and responses
to external influences. We discussed
the elements of the
hydrosphere: the oceans, the continental
ice sheets (Antarctica and
Greenland), mountain glaciers, polar sea
ice, land snow cover, ground
water, lakes, and rivers. There's also
a small amount of water in the
atmosphere in the form of clouds and water
vapor.
We demonstrated how the search engine http://www.google.com
can be
used to find material about topics such
as ice ages, the ozone hole
and greenhouse warming. For most
of the topics we tried, Google
found informative websites. However,
when we typed in greenhouse
warming we found that several of
the leading sites (and in Google,
the leading sites are the ones that have
the most other sites linked
to them) ran counter to the prevailing
scientific opinion on this
topic. The #1 site is devoted to
an article by a well known solar
physicist, that purports to debunk the
greenhouse warming myth.
In deciding how much trust to place in
such an article, the reader
might well consider the author's credentials
(i.e., the extent and
relevance of his/her educational background,
the quality and
relevance of his/her previous publications,
membership on recognized
committees, awards and honors, and citations
by other authors in the
field. It's also worth considering
the author's motivation (i.e.,
sources of financial support) and the
objectivity of writing style.
Examining who the author cites and/or
link to can also be revealing.
It's important to know whether the article
published in a peer
reviewed journal. Peer review is
the scientific community's way of
imposing 'quality control'.
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