Wednesday, July 18, 2012

Cumulus Clouds



Cumulus is the Latin word for pile or heap, and cumulus clouds certainly fit their name! They look like fluffy mounds of whipped cream floating in the sky, and often have a shape similar to that of a cauliflower.

 Cumulus clouds form when relatively warm, moist air rises and cools below the dew point. The moisture in it then condenses into tiny water droplets, which form the cloud. The relative humidity (how "full" the air is with water) helps determine the height at which the moisture condenses at, which is the base of the cloud.
In this little video I made, you can see how the clouds form, with the moist air appearing a light mist rising out of the ground. The moist air is not visible in reality, but I added it to help illustrate the idea:


A cumulus cloud constantly undergoes change, as long as moist air continues to rise under it. The water droplets at the edge of the cloud usually evaporate, so the cloud loses water as it gains it. In a time-lapse, the clouds appear to boil.

Here are the main types of cumulus clouds:

Cumulus Humilis

Cumulus humilis clouds are small things with little vertical development. They indicate that the temperature of the atmosphere in the area does not drop very much with altitude, if at all. When seen in the morning, they signify an unstable atmosphere, possibly resulting in thunderstorms.
These clouds are the most likely type of cumulus cloud to be seen during Winter.

Cumulus Mediocris

Cumulus mediocris has a greater vertical development than that of cumulus humilis, but is not as large as cumulus congestus. When these clouds are seen in the morning or early afternoon, they often indicate storms later in the day.

Cumulus Congestus

Also known as towering cumulus, cumulus congestus are tall, towering clouds that often precipitate (rain, hail, etc.). They are similar to cumulus mediocris, but are a lot larger and taller. They often develop from cumulus mediocris clouds, but may develop from other types of clouds as well. If this type of cloud continues developing, it can become a cumulonimbus cloud. The one in the picture above became a small one within a few minutes.

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Sunday, July 8, 2012

Bird-Watching


Few people watch birds very closely nowadays, or go to any lengths to identify them. That's their loss - bird-watching is fun, educational, and a way to pass the time when you're bored. After bird-watching for a year or two, you can identify birds a lot more easily, and you aren't as clueless when people ask, "What kind of bird is that at your feeder?"

So what do you need to bird-watch? Binoculars are essential; without them, many small markings can be indistinguishable. A field guide is also important. David Allen Sibley's guides are probably best, but anything will work as long as it covers your area thoroughly enough. And that's it. There are other little things that may be helpful, like a camera or a notebook, but these are all you really need.

If you already know a little about bird identification, then you're ready to start looking for birds to identify. But if you're a beginner, you may need a little more help. You might see a large black and white bird land in the snow, and open your field guide to figure out what kind of bird it is. You know the bird you saw must be somewhere in the book, but you don't know where to begin - and it would take you all day to check every single page.

I had the same problem when I first started identifying birds, only the birds were a lot tougher than a Black-Billed Magpie (the black and white bird I just mentioned). I checked the index, only to find a bunch of bird names. That wasn't helpful. I checked everywhere else, trying to find clues as to where I should look in the book. Still no help. In the end, I checked the whole book. I found a few birds that looked like my bird, but the bird was gone so I couldn't compare any more.

What should you do to prevent this from happening?

In good field guides, the birds are grouped according to family, or similar types; the ducks are with the ducks, and the ravens are with the ravens. This makes things simple; once you figure out the family, the possible bird types are greatly reduced.

For beginners, however, determining the family is exactly the problem. If you aren't good at recognizing bird families, try this: look at a lot of pictures of birds, and read about their habitats and behaviors. If you do this, it will make bird identification easier. The longer you spend reading about and studying a bird's characteristics, the more likely you'll be to recognize it when you see it.


Some tips:

- In The Sibley Field Guide to Birds, Sibley has a lot of good rules for birdwatching. Here's a quote: "Practice seeing details. Much of the skill involved in identifying birds is being able to sort out the details of the bird's appearance from a distance."

- Take a notebook with you when you bird-watch. If you see a bird, take notes on the bird's behavior, location and appearance. If you can draw a rough sketch, do that too.

- If you are having trouble identifying a bird, take a few photographs of it. Then you will have a record of it even after it flies away, which can be very helpful.

Swallow
A Violet-Green Swallow in flight
- Sometimes, bird families contain very different-looking birds. Believe it or not, bluebirds are in the same family as robins: both are thrushes. If you run into a family like this, you may wish to break it up and study each genus (a subclass of family) separately.

- Some common bird types to study are: Duck, Finch, Goose, Gull, Hawk, Hummingbird, Pigeon, Swallow, Sparrow. Even if one of them isn't in your area, study it anyway; chances are you'll see it on a vacation.

- When buying binoculars, try them out before you buy them. If you don't, you could end up with something that doesn't focus right, or worse.