Wednesday, June 30, 2010

Satellites Offer Unique Perspective

The image to your left is a visible satellite image of Hurricane Alex, taken early on this Wednesday morning.

The term "visible" comes from the fact that the visible channel senses the solar radiation that is reflected off the surface of the earth. Since the visible channel deals with reflected sunlight, this channel can only be seen during the day. Once the sun goes down, we lose the sunlight, and therefore, the image.

I enjoy looking at the visible satellite, compared to other types of satellites. The reason being is that it shows more features and you can see the different textures when it comes to cloud formations. The bright white clouds in and around Alex show the heavy thunderstorms developing around the center of circulation. If you head east from the center, notice the appearance changes to a milky white. Those are the high, thin cirrus clouds. In this photo, you can also pick out the mid level stratus clouds and even find a few fair weather cumulus clouds as well.

On a daily basis, I look at the visible satellite over the state of Texas. It helps me pick out surface boundaries that might lead to showers and storms. It also better determines how the weather might be changing in the near future.

One of the other forms of satellites we use on a daily basis is the infrared satellite. This is the same shot of Alex, just from a different perspective.

Unlike visible satellite, infrared satellites are good to use 24 hours a day. Infrared satellites measure the temperatures of the cloud tops and emit that temperature source back to outer space.

Typically, the taller the cloud, the colder the cloud tops. Those colder cloud tops show up as the brighter colors in the image above. Notice the dark oranges and red colors located around the center of Alex. That indicates where we have the highest cloud tops and where the showers and storms are strongest.

The first satellite that detected clouds and storm systems came all the way back in 1960. After that, weather forecasting took off, and enabled to us to get a better understanding of how weather works.