That portion of the ionosphere existing between approximately 160 and 400 km above the surface of the Earth, consisting of layers of increased free-electron density caused by the ionizing effect of solar radiation. Note 1: The F region reflects normal-incident frequencies at or below the critical frequency (approximately 10 MHz) and partially absorbs waves of higher frequency. Note 2: The F1 layer exists from about 160 to 250 km above the surface of the Earth and only during daylight hours. Though fairly regular in its characteristics, it is not observable everywhere or on all days. The principal reflecting layer during the summer for paths of 2,000 to 3,500 km is the F1 layer. The F1 layer has approximately 5 ´ 105 e/cm3 (free electrons per cubic centimeter) at noontime and minimum sunspot activity, and increases to roughly 2 ´ 106 e/cm3 during maximum sunspot activity. The density falls off to below 104 e/cm3 at night. Note 3: The F1 layer merges into the F2 layer at night. Note 4: The F2 layer exists from about 250 to 400 km above the surface of the Earth. The F2 layer is the principal reflecting layer for HF communications during both day and night. The horizon-limited distance for one-hop F2 propagation is usually around 4,000 km. The F2 layer has about 106 e/cm3. However, variations are usually large, irregular, and particularly pronounced during magnetic storms.
by IRISHrepublicanARMY January 03, 2004
1) The process of comparing an instrument's output signal with reality. Instruments that measure solar energy tend to "drift", that is, their output signals do not mean the same thing from one time period to another. Because of this, they are periodically (annually or semi-annually) re-calibrated against more reliable instruments.
2) Adjusting a measuring instrument to make it accurate. The set of operations which establish, under specified conditions, the relationship between values indicated by a measuring instrument or measuring system and the corresponding values of a quantity realized by a reference standard.
3) The act of adjusting the color of one device relative to another, such as a monitor to a printer, or a scanner to a film recorder. Or, it may be the process of adjusting the color of one device to some established standard.
2) Adjusting a measuring instrument to make it accurate. The set of operations which establish, under specified conditions, the relationship between values indicated by a measuring instrument or measuring system and the corresponding values of a quantity realized by a reference standard.
3) The act of adjusting the color of one device relative to another, such as a monitor to a printer, or a scanner to a film recorder. Or, it may be the process of adjusting the color of one device to some established standard.
by IrishRepublicanArmy December 26, 2003
by IrishRepublicanArmy December 21, 2003
What I find surprising is how easy it is to get a driver's license in the Unites States (well, in Virginia, at least). First you get your learner's permit. This is sinfully easy, I spent two hours at the DMV waiting, and 10 minutes taking the tests. First there is a sign test, which I don't understand how someone who hasn't spent thier entire life in a barn could possably get the one question wrong to fail (there are 10 questions). Next is a "driving thoery" test, which is nothing more then common sense, however many people seem to fail that also. The next requirement is that you take classroom Driver's Education. All you have to do is sit through a boring class (you spend your whole school day doing it anyway), you will have a grand total of three tests and two homework assignments for the class, but people still fail this also. The third requirement is taking behind-the-wheel driver's education. ALL YOU HAVE TO DO IS DRIVE THE CAR. Listening to an adult is not hard, considering you won't have to drive with one in the car after this. But many people apperntly do not posses the motor skills/eye-hand correnadtion to 1) make a left turn 2) signal a lane change 3) PARK FOR HEAVEN'S SAKE 4) obey the speed limit 5) stay in your lane etc. etc. Finally you take the practical driving test, which is just like behind-the-wheel execpt the person in the right seat has a clipboard with your name on it.
I don't understand how people can think getting a driver's license in this country is hard. In other places, such as Europe, I could understand, because in places like that you actully have to prove that you know how to drive a car.
by IrishrepublicanArmy March 13, 2004
a highway for high-speed traffic, with few or no intersections and a divider between lanes of traffic moving differant directions
by irishrepublicanarmy January 02, 2004
A high-quality, relatively low-risk investment; the term usually refers to stocks of large, well-established companies that have performed well over a long period.
by IrishRepublicanArmy February 11, 2004
Feb. 13th, the day before Valentine's Day. Because so many people don't have relationships (or do, and they hate Valentine's Day anyway), Feb 13th is the day where single people do nothing, there are no cards, no flowers or anything like that.
Happy singles awareness day!
by IrishRepublicanArmy February 14, 2004