Virga or fall streaks are a form of precipitation that evaporates before it hits the ground. Low humidity and high temperatures can cause rain to evaporate completely right after its release from a cloud. At high altitudes, the precipitation falls mainly as ice crystals before melting and finally evaporating.
Virga also has a role in seeding storm cells. It seeds the storm with small particles from one cloud that are blown into neighboring supersaturated air and act as “food” for the next storm cloud to start forming.
Virga can produce dramatic and beautiful scenes during a sunset. The light can be caught by the streamers of falling precipitation and light it up into so many beautiful colors.

Posted under science, weather

Altocumulus Castellanus (ACCAS), named for its tower-like pillars that billow upwards from the base of the cloud. Castellanus are the clouds that storm chasers look for on the morning of severe weather. Chasers look for these because they tell us that there is evidence of mid-atmospheric instability that is needed to supports supercell thunderstorms. They may be an indication of heavy showers and thunderstorms, if there is a lifting force at the surface that can connect to the unstable layer in the mid-levels. If they do interact, the Castellanus clouds may develop into cumulonimbus storm clouds.

Posted under science, weather

Have you ever wondered how many types for clouds there are?We have all heard of the three main categories, Cirrus, Cumulus and Stratus. However, there are so many different forms, features and species of each cloud that are used to describe the kind of cloud that you are looking at. Clouds are divided into the three categories based on the Latin words, which refer to the process of development. From there, each of these categories has several cloud genera. Ten cloud genera are obtained by cross-classification of the stratus and cumulus categories. They are separated by the prefix cirro, alto and low. Examples: cirrostratus and altocumulus. When looking at a species of clouds, that would be the individual or special cloud formation in one of the genera. For instance, the super-cool lenticular cloud (UFO Cloud) is species of cirrocumulus, altocumulus and stratocumulus. There are 13 different cloud species. The last classification before we get to the category all by itself is the main cloud features. This one we have all seen or at least heard of maybe in one of the blogs. Mammatus on the list of main cloud features as well the pileus cloud. Cloud features are usually created from how they are formed, which would bring the total in this classification to 21. Last but not least is the storm associated clouds. This is where you would find your funnel clouds and anvils. There are about 50 different types in the list and they have to do with stormy weather.

Posted under science, weather

It is going to be a whole week of flybys courtesy of the International Space Station.  Starting tomorrow evening and lasting through Friday, we get to watch what will be a small dot in the sky fly over head.  Now you have to check the list, because some days have a double flyby.  Also, take note of the direction you need to look as well as the angle above the horizon.  Best locations to get a glimpse of the station would be open areas away from city light and tall trees. 

Posted under science, space

Have you ever wonder what the Earth and Moon look like from other planets. We’ve seen pictures from Mars, but what about somewhere closer to Mercury or the Sun. NASA’s MESSENGER spacecraft is on a scavenger hunt around Mercury and the Sun looking for vulcanoids, a long-sought population of sun-grazing asteroids. While searching for these asteroids, it took this picture of our planet and moon from 114 millions miles away. To give you a better understanding of how far that is, the average separation between the Earth and the Sun is 93 million miles.
(That’s us in the lower left conrner in the picture)

Posted under science, space

Kelvin-Helmholtz wave clouds form between two layers of air that have different densities, travel at different speeds and in the opposite direction. You need a warm, less dense layer of air over a layer of colder, denser air. The upper layer of air is moving faster then the lower layer scooping the top of the lower layer and forming these wave-like rolling clouds. In order for us to see this layer of difference, there has to be enough water vapor in the air for a cloud to form. These clouds often form on windy days where there is a difference in densities of the air.
Have trouble seeing this happen… take a look at this time-lapse video. Keep on eye near the horizon; you will start to see the layers moving at different speeds and directions when it starts to clear up.

http://www.atmos.washington.edu/images/webcam0/movies/20100722.mov

Posted under science, weather

Julie McGuire of Mount Morris got these shots of a roll cloud this morning. Roll clouds are really cool to see because if you look really close they appear to roll, just like a rolling pin! They are usually associated with an outflow from a dying (or dead) thunderstorm. Great shots Julie! Thanks for sharing. -ES

Posted under science, weather

The International Space Station is doing a flyby over Rockford not once but four times. Sky conditions look good each night, so mark your calendars and enjoy the view!

Posted under science, space

Since some of us are still in the holiday spirit, I thought why not talk about fireworks. Now, this just goes to show you of how big of a science geek I am. Have you ever wonder what chemical makes the fireworks so colorful. Here is a list of chemicals that are added to make the fireworks so pretty.

Aluminum is used to make silver and white flames and sparks.
Antimony is used to make glitter effects.
Barium creates the color green.
Calcium salts produce orange fireworks.
Copper compounds produce the color blue.
Iron is used to make sparks. The temperature of the metal determines the color of the spark.
Lithium and Strontium salts create the color red to fireworks.
Magnesium burns a very bright white.
Potassium when added to a sparking metal will add a violet color to it.
Phosphorus can add a glow in the dark effect.
Sodium makes gold or yellow fireworks.
Titanium flakes add silver sparks.
Zinc is a bluish white metal that is added to create smoke effects.

So, if by any chance you have leftover fireworks, fire a few up this evening and check out what chemicals are in yours.

Posted under science, technology

NASA’s space shuttle program will keep going until next year. The space agency made it official yesterday that more time is needed to get the next set of cargo ready for the final two shuttle missions. Managers agreed to push back the Discovery launch until Nov. 1,2010, instead of its original date in September. The very last mission has a launch date of Feb. 26, 2011. That means Space Shuttle Endeavour will close out the 30-year space program by delivering an Alpha Magnetic Spectrometer to the space station.

No matter what the outcome is, shuttle Atlantis will be on standby, just in case it is needed for a rescue mission for Endeavour’s crew.

Posted under science, space