S'COOL: How accurate do you need to be?
Choosing which satellite matches your observation time is simply a help to
you or others who may want to analyze your report later.
Determining Cloud Cover can also be interesting, since there are
some well-known optical illusion effects at play here. A couple suggestions:
get several (or lots) of independent guesses, then take an average. For
example, each student or group of students can independently pick a value.
Another helpful hint is to make yourself some cloud cover models.
Take a piece of blue paper (the sky). Cut out a known fraction of a piece
of white paper (we suggest 5, 50, and 95 percent at least - which are our
cloud cover boundaries). Tear up the white paper into "clouds" and glue them
onto your "sky". It's best
to have several people do this, as clouds come in different sizes and shapes.
For example, 50% cloud cover could mean half the sky is clear; or it could
mean lots of little cumulus clouds. These look quite different visually. Try
it!
Determining Visual Opacity is not meant to be an exact science. If
the cloud is so thin you can see blue sky - or even the moon! - through it,
call it transparent. If the cloud is so thick that the day is dark and dreary,
call it opaque. In between, things are a bit fuzzy. Again, a good way to
come to an answer is to have everybody make an independent determination, then
vote or average the results.
Identifying and counting contrails is sometimes easy and sometimes a
challenge. On the days when it is harder, keep in mind that you are the only
source of this kind of data we have, and just do the best you can. On really
heavy days, you might want to estimate the fraction of sky covered by contrails
and record that in the comments.
The Surface Measurements are totally optional. If you have instruments
to measure these, we are happy to get the information. The most important
measurement here is temperature, followed by relative humidity, then pressure.
If you do record something be sure that you select the correct units!
Measuring pressure has some little twists. If you are interested,
read further.
Identification
It is very important to accurately record your login. If
we don't know where you are, we cannot use the information. If you send
reports by mail or fax, your location and/or password will also help
us to correctly enter your reports.
Time/Satellite
It is also very important to correctly record the date, and particularly
the time, of the observation. If you get these wrong, either we won't be able
to match with the satellite; or we will match with the wrong satellite
observation. For help converting your local time to Universal time, use
this worksheet.
Cloud Observations
Determining Cloud Type is sometimes a challenge, but, for our purposes,
you may not need to worry too much. The satellite cannot tell the difference
between stratus and stratocumulus, for example. It will identify both as
"low, water clouds". So, if you are debating between two or three low cloud
types, you can stop worrying and just pick one. Similarly, if you are debating
between two or three high cloud types, these will all be described by the
satellite as "high, ice clouds", so again you can just pick one. What is
most important is to correctly discrimate between clouds at different heights.
And, since there is no frame of reference (unless you live next to a mountain
or a really tall skyscraper) to determine cloud height, you have to identify
the cloud type well enough to pick Cloud Height.
Ground Observations
The cloud observation is the most important thing, so if you got this far
relax! Surface cover information tells us something about the background
against which we are trying to detect clouds. The most important thing here
is to report snow or ice, which are both bright and cold, like clouds. Keep in
mind that the satellite views an area about a half to one square kilometer at
a time, so if there is one small patch of snow or ice don't check this. As
with all of these choices, you should check them if they are true for most
of the area around you.
Comments
Try this philosophy for the comments: if someone else pulls up your
observation, what would you like them to know about what you observed?
S'COOL
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Observation Database