Introduction to Clouds
From Satellite Data to Images of Clouds
The Satellite Imaging Process
The previous page illustrated that the data produced by the satellite
is a number for each location in a grid. A portion of one such grid is
shown below.
|
Satellite Data: Cloud Optical Thickness for Storm 14 (April 10-14), 1988
|
| 11 |
47.3 |
47.3 |
41.3 |
41.3 |
19.1 |
19.1 |
1.7 |
1.7 |
0.3 |
0.3 |
0.0 |
0.0 |
0.0 |
0.0 |
0.0 |
0.0 |
1.2 |
1.2 |
0.0 |
0.0 |
0.0 |
9.9 |
9.9 |
| 10 |
60.4 |
60.4 |
9.9 |
9.9 |
2.1 |
2.1 |
1.0 |
1.0 |
0.0 |
0.0 |
4.5 |
4.5 |
3.2 |
3.2 |
2.4 |
2.4 |
2.1 |
2.1 |
0.9 |
0.9 |
5.2 |
10.8 |
10.8 |
| 9 |
66.9 |
26.1 |
26.1 |
2.8 |
2.8 |
1.2 |
1.2 |
5.5 |
5.5 |
9.4 |
6.3 |
6.3 |
2.4 |
2.4 |
3.6 |
3.6 |
1.0 |
1.0 |
1.2 |
2.5 |
2.5 |
10.6 |
10.6 |
| 8 |
33.2 |
9.2 |
6.8 |
6.8 |
1.4 |
1.4 |
12.2 |
22.2 |
22.2 |
13.3 |
13.3 |
12.4 |
12.4 |
14.0 |
3.9 |
3.9 |
3.4 |
3.4 |
1.3 |
4.8 |
4.8 |
8.0 |
8.0 |
| 7 |
4.1 |
4.1 |
9.7 |
2.0 |
2.0 |
3.0 |
21.8 |
21.8 |
12.0 |
12.0 |
8.0 |
4.0 |
4.0 |
23.1 |
14.5 |
14.5 |
4.6 |
4.6 |
2.2 |
1.0 |
1.0 |
3.1 |
10.4 |
| 6 |
1.0 |
0.3 |
8.3 |
8.3 |
0.8 |
4.0 |
4.0 |
11.2 |
11.2 |
4.1 |
5.7 |
5.7 |
1.8 |
17.4 |
17.4 |
29.6 |
9.5 |
9.5 |
4.9 |
4.2 |
4.2 |
3.6 |
4.0 |
| 5 |
1.0 |
1.0 |
1.3 |
0.8 |
0.8 |
1.2 |
0.8 |
0.8 |
0.8 |
1.5 |
3.3 |
3.3 |
1.0 |
34.7 |
34.7 |
36.5 |
13.8 |
13.8 |
3.4 |
5.5 |
5.5 |
5.5 |
3.3 |
| 4 |
0.5 |
0.5 |
0.4 |
0.6 |
0.3 |
0.3 |
1.0 |
0.6 |
0.7 |
0.7 |
0.8 |
0.8 |
0.8 |
17.1 |
44.8 |
27.2 |
27.2 |
10.2 |
3.8 |
3.8 |
1.1 |
4.0 |
2.2 |
| 3 |
3.0 |
0.0 |
0.0 |
0.5 |
0.5 |
0.2 |
0.2 |
0.2 |
0.3 |
0.5 |
0.5 |
3.0 |
26.6 |
72.0 |
72.0 |
18.7 |
8.9 |
4.6 |
4.6 |
2.2 |
0.7 |
0.2 |
0.2 |
| 2 |
0.4 |
0.0 |
0.7 |
0.7 |
0.7 |
1.0 |
1.6 |
1.6 |
1.2 |
2.0 |
4.7 |
25.5 |
25.5 |
66.9 |
12.4 |
12.0 |
12.0 |
5.2 |
1.3 |
5.7 |
1.8 |
1.8 |
2.1 |
| 1 |
1.1 |
0.5 |
1.4 |
0.2 |
0.2 |
0.3 |
0.8 |
0.8 |
2.2 |
2.2 |
3.6 |
37.4 |
48.7 |
31.7 |
31.7 |
26.6 |
7.9 |
2.4 |
0.9 |
0.9 |
1.1 |
2.1 |
1.8 |
| 0 |
4.9 |
2.6 |
1.5 |
0.8 |
1.0 |
1.0 |
1.3 |
1.7 |
3.3 |
7.2 |
62.4 |
62.4 |
39.3 |
40.3 |
20.9 |
4.7 |
2.6 |
2.6 |
0.8 |
1.7 |
2.0 |
3.5 |
1.8 |
|
0 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
13 |
14 |
15 |
16 |
17 |
18 |
19 |
20 |
21 |
22 |
With digitized data a scientist can mathematically manipulate or "view"
the data using a variety of imaging software. Any color scheme can be
used for data visualization. When the table above is interpreted with
imaging software, different numerical values are assigned different colors.
The resultant plot shows the pixels of various colors. In the image
below, each color indicates an average value of cloud thickness over a
specific geographical area (grid box). This image gives detailed,
quantified information about changes in cloud thickness, which
can help to classify a cloud.
Cloud optical thickness for Storm 14 (April 10-14),
1988.
Which color corresponds to the most optically thick clouds? What does
the color purple indicate in the image?
Can you locate these thickest clouds in the data table above? What are
the actual values of their optical thicknesses?
The image below was created with the same data, but using a
grayscale color scheme. The numbers in the data are assigned
different shades of gray, giving the most optically thick clouds a
white appearance. This image displays less information about detailed
cloud characteristics, but looks more like the standard television weather
image.
Grayscale image of cloud optical thickness for Storm 14
(April 10-14), 1988
If you note the appearance of this small dataset you can make out
the (typical) shape of the storm. A common practice is to then
superimpose a map over the image of the entire dataset. It then
becomes apparent that these clouds are part of a storm system that
may cover almost one quarter of the continental United States. A sample
satellite picture is shown below illustrating the similar shape of the
storm clouds such as in the above dataset.
Infrared satellite image of North America from the Geostationary
Operational Environmental Satellite (GOES)-East, February 4, 1997.
The form below allows you to retrieve similar satellite images
of clouds. For example, you might want to see how the clouds
appear over the United States today. Remember how the image was
produced.
Now that you know how clouds researchers obtain some of their
data, you are ready to proceed to the Data Analysis section, where
you will begin to work with some of this data.
