Or Maybe Do Send Them. On a recent flight to Kenya, my husband sat beside a Kenya small business owner. Her clothing shop sells locally made dresses using Kenyan materials and employees. She said these used clothes imports make it incredibly difficult to sustain her business.
Some planes in the sky leave trails that persist and spread, and other planes, in the same sky, leave short-lived trails, or no trails at all.
Contrails are actually a type of cirrus cloud. When the air is wet and cold enough the trails can stay around for a long time, and sometimes spread out. So you see helpful images like this. But this is wrong. Contrails can fade away, and contrails can persist and spread. It depends on the air they are formed in.
Now there are two main reasons why some planes leave trails and some nearby planes do not. The less common reason, is that different planes have different engines. Some engines will leave a contrail in air where another engine will not. Here, for example are an Airbus A maiden flight: You can also get a similar effect with engines at different power settings, especially if it affects the exhaust temperature.
This can occasionally be seen with high altitude refueling, when the plane being refueled cuts the throttle to near idle in order to separate from the tanker.
The planes are at different altitudes. The reason that one plane makes contrails, or makes contrails that persist, and the other plane does not, is that they are in different regions of air.
When the plane is in wet air, it makes a contrail. In dry air it does not. Surely, you might object, they would have to be miles apart? Well, no, and that brings me to another point I fear I must emphasise: Wet and dry air can exist within a few feet of each other. Consider, for example, clouds: Look at the bottom of those clouds, see them extend off into the distance.
They form a layer at a specific altitude. Above that altitude there are clouds. Below it there are no clouds. The difference between clouds and no clouds is just a few feet.
Now those are low altitude cumulus couds. Again they are in a flat layer. The different between being in the layer and not in the layer is just a few feet. This layering of the air into wet and dry layers is not limited to clouds. Seemingly clear air also contains exactly the same kind of variation in layers.
If it were above or below it then it would not. But, you may cry, the planes are at the same altitude. These planes fly at 30, to 40, feet.
I took one image of a jet nominally at 35, feet. Then scaled it for 34, If the top plane was flying at 20, feet, then the bottom would be at 18, feet, still nearly 2, feet apart, and looking pretty much the same to the naked eye. And that is with the same model of plane, directly overhead, and right next to each other.
A situation that almost never occurs. Just look at this: Or from the ground, with the planes at 30, feet. They look about the same height, right?Nov 19, · "All my black friends have a bunch of white friends. And all my white friends have one black friend.". That's the memorable punchline of a Chris Rock bit from on interracial friendships.
In the world of crowdfunding, there’s no such thing as a sure thing. But with this handy guide, you'll be able to spot the signs of a sketchy project and decrease your chances of getting burned. Parents everywhere often hear this from their children: “I saw a ghost.” For the parent unaware of exactly how to handle such a delicate situation, the following do’s and don’ts might come in handy.
dont - traduction français-anglais. Forums pour discuter de dont, voir ses formes composées, des exemples et poser vos questions.
Gratuit. The E-Myth Revisited: Why Most Small Businesses Don't Work and What to Do About It [Michael E. Gerber] on timberdesignmag.com *FREE* shipping on qualifying offers. In this first new and totally revised edition of the , copy underground bestseller, The E-Myth. In software engineering, don't repeat yourself (DRY) is a principle of software development aimed at reducing repetition of software patterns, replacing it with abstractions or using data normalization to avoid redundancy..
The DRY principle is stated as "Every piece of knowledge must have a single, unambiguous, authoritative representation within a system".