ection 6
Obtaining Images and Data via the Internet
Listed below are a sequence of commands that will allow you to get the most recent
copy of a document that lists weather data and satellite images available on the
Internet. Methods and access to satellite imagery are changing rapidly so this informa-
tion may not be applicable to all users and/or may be outdated in the near future.
Before you begin, you must be able to access your account at a local university or
other site via modem and access the Internet from that account. In addition, you must
have the ability to store files temporarily on your university account. Finally, you will
need to determine your complete Internet address. With these tasks accomplished, dial
in to your account and enter these commands after the prompt:
ftp vmd.cso.uiuc.edu
The initial command “ftp” simply means “file transfer protocol.” ftp is a standard form of
communicating within Internet. The remainder of this command is simply the address
of a computer that is on the Internet.
If the network isn't busy, you will be greeted with a prompt to login. The best time to
access the Internet is before 10 am or after 3 pm. For Internet transfers of the type we
will be discussing here (called “anonymous ftp”), your login is always “anonymous.”
Your password is always your full address. Your address is typically your login name fol-
lowed by the address of your home account. For example, John Doe who works at
the University of Maryland may have an address like [email protected].
login: anonymous
password: your address
Once you have been logged in at vmd.cso.uiuc.edu, you will need to move from your
starting point to the directory that has the weather data information. You will do this
by changing directories. Most locations on the Internet use the UNIX system. The com-
mand to change directories in UNIX is “cd”.
cd wx
Then list all the files in the “wx” directory:
ls
You can use the wildcard “*” to list only those files with certain characters. For example
to see all files with the extension “doc”, enter the command below:
ls *.doc
Before downloading, check the size of each file with the command:
SAT E L L I T E IM A G E S A N D
T H E IN T E R N E T
S
