"on the pole shining inside it. Wind direction is the opposite of the direction in which the windsock is pointing (note that wind directions are conventionally specified as being the compass point from which the wind originates; so a windsock pointing due north indicates a southerly wind). Wind speed is indicated by the windsock's angle relative to the mounting pole; in low winds, the windsock droops; in high winds it flies horizontally. Alternating stripes of high visibility orange and white were initially used to help to estimate the speed of wind. Each stripe adds up 3 knots to the estimated"
"Weather vane A weather vane, wind vane, or weathercock is an instrument for showing the direction of the wind. It is typically used as an architectural ornament to the highest point of a building. The word ""vane"" comes from the Old English word ""fana"" meaning ""flag"". Although partly functional, weather vanes are generally decorative, often featuring the traditional cockerel design with letters indicating the points of the compass. Other common motifs include ships, arrows and horses. Not all weather vanes have pointers. When the wind is sufficiently strong, the head of the arrow or cockerel (or equivalent depending on the"
"tube. A fluid flow velocity tool, the Pitot tube is primarily used to determine the air velocity of an aircraft. Wind speed is a common factor in the design of structures and buildings around the world. It is often the governing factor in the required lateral strength of a structure's design. In the United States, the wind speed used in design is often referred to as a ""3-second gust"" which is the highest sustained gust over a 3-second period having a probability of being exceeded per year of 1 in 50 (ASCE 7-05). This design wind speed is accepted by"
"Trailing cone Trailing cones (or trailing wires as they are often incorrectly called or trailing static cones), were first developed and tested in the 1950s and 1960s as a simple means of calibrating the static pressure (altitude reporting) error of an aircraft's pitot-static system. It does this by giving an accurate measurement of the ambient atmospheric pressure (static pressure) well clear of the aircraft's fuselage. The trailing cone system trails at least one fuselage length behind the aircraft (SpaceAge Control) via a high-strength pressure tube. Static pressure is measured forward of the cone by several static ports. The cone stabilizes"
"Horizontal convective rolls Horizontal convective rolls, also known as horizontal roll vortices or cloud streets, are long rolls of counter-rotating air that are oriented approximately parallel to the ground in the planetary boundary layer. Although horizontal convective rolls, also known as cloud streets, have been clearly seen in satellite photographs for the last 30 years, their development is poorly understood, due to a lack of observational data. From the ground, they appear as rows of cumulus or cumulus-type clouds aligned parallel to the low-level wind. Research has shown these eddies to be significant to the vertical transport of momentum, heat,"
"in the boardroom so senior officers were always aware of the wind direction when they met. Modern ""aerovanes"" combine the directional vane with an anemometer (a device for measuring wind speed). Co-locating both instruments allows them to use the same axis (a vertical rod) and provides a coordinated readout. According to the Guinness World Records, the world's largest weather vane is a Tío Pepe sherry advertisement located in Jerez, Spain. The city of Montague, Michigan also claims to have the largest standard-design weather vane, being a ship and arrow which measures 48 feet tall, with an arrow 26 feet long."
"both sides of the staff to indicate wind speed. In the United States, the change to the modern convention of flags shown on one side of the staff to indicate wind speed took effect on August 1, 1941. Along with wind direction, cloud cover is one of the oldest atmospheric conditions to be coded on a station model. The circle in the middle of the station model represents cloud cover. In the United Kingdom, when the observation is taken from an automated weather observation site, the shape is a triangle. If the shape is completely filled in, it is overcast."
"with two ports, pitot and static, that is normally used in measuring the airspeed of aircraft. The pitot port measures the dynamic pressure of the open mouth of a tube with pointed head facing wind, and the static port measures the static pressure from small holes along the side on that tube. The pitot tube is connected to a tail so that it always makes the tube's head to face the wind. Additionally, the tube is heated to prevent rime ice formation on the tube. There are two lines from the tube down to the devices to measure the difference"
"in degrees, North corresponds to 0°/360°, East to 90°, South to 180° and West to 270°. Compiling a wind rose is one of the preliminary steps taken in constructing airport runways, as aircraft experience greater lift when pointing into the wind. Wind rose A wind rose is a graphic tool used by meteorologists to give a succinct view of how wind speed and direction are typically distributed at a particular location. Historically, wind roses were predecessors of the compass rose (found on charts), as there was no differentiation between a cardinal direction and the wind which blew from such a"
"altitude and the air decreases in density and temperature, the speed of sound also decreases. Close to the speed of sound, an aircraft becomes susceptible to buffeting caused by shock waves produced by flying at transonic speeds. Thus, as the speed of sound decreases, so the maximum safe operating speed of the aircraft is reduced. The ""barber pole"" needle moves to indicate this speed. Flying ""on the barber pole"" therefore means to be flying the aircraft as fast as is safe to do so in the current conditions. ""Barberpole"" is a phrase used to describe the striped output of indicators"
"Trend type forecast A trend type forecast (TTF) also known simply as a trend, is an aviation weather forecast written by a real person on location at a major airport or military base. A TTF is a professionally considered forecast for weather over a two-hour period, and is based on an actual weather report, such as a METAR or SPECI and appended to the end of it. A TTF is similar to or sometimes in addition to a TAF, a terminal aerodrome forecast, but during the TTF's validity period is considered superior to a TAF. In this example the METAR"
"faces the direction that the wind is blowing from; its tail, with the smaller opening, points in the same direction as the wind is blowing. Modern instruments used to measure wind speed and direction are called anemometers and wind vanes, respectively. These types of instruments are used by the wind energy industry, both for wind resource assessment and turbine control. In situations where modern instruments are not available, an index finger can be used to test the direction of wind. This is accomplished by wetting the finger and pointing it upwards. The side of the finger that feels ""cool"" is"
"amount of deflection from vertical that is observed, while the wind direction is provided by which way this deflection occurs. A mirror, located under the telltale, and a calibration ""cross,"" above (as observed through the mirror) are employed to increase the accuracy of the measurement. Either the SSI or RAC cameras could make this measurement, though the former was typically used. Periodic observations both day and night aid in understanding the diurnal variability of wind at the ""Phoenix"" landing site. The wind speeds ranged from 11 km to 58 km per hour. The usual average speed was 36 km per"
"Wind rose A wind rose is a graphic tool used by meteorologists to give a succinct view of how wind speed and direction are typically distributed at a particular location. Historically, wind roses were predecessors of the compass rose (found on charts), as there was no differentiation between a cardinal direction and the wind which blew from such a direction. Using a polar coordinate system of gridding, the frequency of winds over a time period is plotted by wind direction, with color bands showing wind speed ranges. The direction of the longest spoke shows the wind direction with the greatest"
"Relative wind In aeronautics, the relative wind is the direction of movement of the atmosphere relative to an aircraft or an airfoil. It is opposite to the direction of movement of the aircraft or airfoil relative to the atmosphere. Close to any point on the surface of an aircraft or airfoil, the air is moving parallel to the surface; but at a great distance from the aircraft or airfoil the movement of the air can be represented by a single vector. This vector is the relative wind or the ""free stream velocity vector"". The angle between the chord line of"
"ambient intelligence, medical, and industrial tasks. Context-based processing and services, in particular location-context, are of key interest ..."" (See Music (acoustic illusion), infra.) The term ""on the barber pole"" is pilot jargon that refers to flying an aircraft at the maximum safe velocity. The airspeed Indicator on aircraft capable of flying at altitude features a red/white striped needle resembling a barber pole. This needle displays the V (Maximum Operating Velocity) or—at altitude—the M (Mach Limit Maximum Operating Speed) of the aircraft. This needle also indicates the maximum operating Mach number above the VMO/MMO changeover level. As the aircraft increases in"
"of these arrows has a mechanical equivalent in the bombsight. The direction of the yellow arrow is that of the aircraft itself, represented in the bombsight by its mounting to the aircraft fuselage. The length of the yellow arrow is set by rotating the air speed drum, carrying the windage calculator with it. The milled head is used to rotate the wind bar to the same angle as the wind, in this case about 120 degrees. This would leave the wind bar almost at right angles to the drift bar, with the wind speed knob easily accessible on the left."
"speed, which is shown in knots. The station model uses a wind barb to show both wind direction and speed. The wind barb shows the speed using ""flags"" on the end. Winds are depicted as blowing from the direction the flags are facing. Therefore, a northeast wind will be depicted with a line extending from the cloud circle to the northeast, with flags indicating wind speed on the northeast end of this line. Once plotted on a map, an analysis of isotachs (lines of equal wind speeds) can be accomplished. Isotachs are particularly useful in diagnosing the location of the"
"tip of the green arrow, compared to its current position at the base of the arrow. A powerful wind is blowing from just off the port wing of the aircraft, blowing towards about 120 degrees. If the aircraft simply points toward the target, along the green arrow, the wind will cause it to drift to the right. In order to approach the target properly, the aircraft needs to turn to the left until the portion of its airspeed equal to the wind speed cancels out the drift. The resulting direction is represented by the yellow arrow. On the CSBS each"
"Lind was not the first it was the most practical and best known anemometer of this type. If the wind blows into the mouth of a tube it causes an increase of pressure on one side of the manometer. The wind over the open end of a vertical tube causes little change in pressure on the other side of the manometer. The resulting elevation difference in the two legs of the U tube is an indication of the wind speed. However, an accurate measurement requires that the wind speed be directly into the open end of the tube; small departures"
"indicates it is from EGXE (RAF Leeming) at 1150 UTC on Day 6. The observation follows (see METAR for explanation), with the Trend added to the end of the observation. The Trend reads TEMPO 6000 SHRA SCT020 WHT i.e. Temporary deterioration to 6 km visibility in a moderate rain shower with scattered at 2000 ft, colour state White. Trend type forecast A trend type forecast (TTF) also known simply as a trend, is an aviation weather forecast written by a real person on location at a major airport or military base. A TTF is a professionally considered forecast for weather"
"gradient wind is similar to the geostrophic wind but also includes centrifugal force (or centripetal acceleration). Wind direction is usually expressed in terms of the direction from which it originates. For example, a ""northerly"" wind blows from the north to the south. Weather vanes pivot to indicate the direction of the wind. At airports, windsocks indicate wind direction, and can also be used to estimate wind speed by the angle of hang. Wind speed is measured by anemometers, most commonly using rotating cups or propellers. When a high measurement frequency is needed (such as in research applications), wind can be"
"plotted on surface weather maps uses a wind barb to show both wind direction and speed. The wind barb shows the speed using ""flags"" on the end. Winds are depicted as blowing from the direction the barb is facing. Therefore, a northeast wind will be depicted with a line extending from the cloud circle to the northeast, with flags indicating wind speed on the northeast end of this line. Once plotted on a map, an analysis of isotachs (lines of equal wind speeds) can be accomplished. Isotachs are particularly useful in diagnosing the location of the jet stream on upper"
"tell-tale, developed by the University of Aarhus in Denmark, as part of its ""Meteorological Station"". It is a small tube that is deflected by the martian wind. The science payload’s stereo camera recorded images of the tell-tale that are used to determine wind direction and speed. Tell-tale (spacecraft) In space systems a tell-tale is a single-bit status indicator that is included in telemetry or is used within the spacecraft's on-board software to signal conditions that must be tracked or acted upon, especially when the status changes. A tell-tale may continually change as the status it is tracking changes, or, it"
"in pressure of the two lines. The measurement devices can be manometers, pressure transducers, or analog chart recorders. In the tube anemometer the dynamic pressure is actually being measured, although the scale is usually graduated as a velocity scale. If the actual air density differs from the calibration value, due to differing temperature, elevation or barometric pressure, a correction is required to obtain the actual wind speed. Approximately 1.5% (1.6% above 6,000 feet) should be added to the velocity recorded by a tube anemometer for each 1000 ft (5% for each kilometer) above sea-level. At airports, it is essential to"
"may have to take into account. To convert wind speeds from one averaging time to another, the Durst Curve was developed which defines the relation between probable maximum wind speed averaged over t seconds, V, and mean wind speed over one hour V. Wind speed Wind speed, or wind flow velocity, is a fundamental atmospheric quantity caused by air moving from high to low pressure, usually due to changes in temperature. Note that wind direction is usually almost parallel to isobars (and not perpendicular, as one might expect), due to Earth's rotation. Wind speed affects weather forecasting, aviation and maritime"
"a standard rate or ""rate one"" turn. Coordinated flight indication is obtained by using an inclinometer, which is recognized as the ""ball in a tube"". An inclinometer contains a ball sealed inside a curved glass tube, which also contains a liquid to act as a damping medium. The original form of the indicator is in effect a spirit level with the tube curved in the opposite direction and a bubble replacing the ball. In some early aircraft the indicator was merely a pendulum with a dashpot for damping. The ball gives an indication of whether the aircraft is slipping, skidding"
"Tractor. This landmark is located at the Canadian Tractor Museum. The term ""weathervane"" is also a slang word for a politician who has frequent changes of opinion. The National Assembly of Quebec has banned use of this slang term as a slur after its use by members of the legislature. Weather vane A weather vane, wind vane, or weathercock is an instrument for showing the direction of the wind. It is typically used as an architectural ornament to the highest point of a building. The word ""vane"" comes from the Old English word ""fana"" meaning ""flag"". Although partly functional, weather"
"to change direction with altitude is called steerage. In the ideal case, in the northern hemisphere, wind direction turns to the right with an increase in altitude. This is due to the Coriolis effect. Winds spiral clockwise, when seen from above, out of a high pressure system and counter clockwise into a low pressure system. However, air traveling close to the ground will tend to move in more of a straight line from high to low pressure due to drag with the ground. Thus, a pilot may hope to find a turn to the left during the descent to landing."
"from: In aviation, airspeed is typically measured in knots. In weather stations with high wind speeds, the pitot tube is modified to create a special type of anemometer called pitot tube static anemometer. Notes Bibliography Pitot tube A pitot ( ) tube, also known as pitot probe, is a flow measurement device used to measure fluid flow velocity. The pitot tube was invented by the French engineer Henri Pitot in the early 18th century and was modified to its modern form in the mid-19th century by French scientist Henry Darcy. It is widely used to determine the airspeed of an"
"was named ""Smiles""). Aircraft speed is often measured in knots and elevation in feet (flight level) in many countries. For both domestic and international routes, U.S. airlines set luggage size and weight restrictions in terms of customary units. Conversely, international airlines that fly to the U.S. often restrict baggage to metric sizes. The temperatures in aviation-related weather reports are given in degrees Celsius in the United States. For carry on luggage, the Transportation Security Administration restricts liquids to 3.4 fluid ounces (100 mL). Originally, the agency planned to restrict to 3 ounces but switched it to 3.4 oz / 100"
"Winds aloft Winds aloft, officially known as the winds and temperatures aloft forecast, (known as ""FD"" in the US and Canada, but becoming known as ""FB"", following the World Meteorological Organization [WMO] nomenclature), is a forecast of specific atmospheric conditions in terms of wind and temperature at certain altitudes, typically measured in feet (ft) above mean sea level (MSL). The forecast is specifically used for aviation purposes. The components of a winds and temperatures aloft forecast are displayed as DDss+/-TT: FBUS31 KWNO 190440 ABR, ABI, and ALS are the weather station abbreviations used in this report. Wind speeds over 99"
"with the wind. The pilot controls the altitude either by heating the air more or by releasing ballast weight. The wind direction usually changes with altitude, so crude directional control can be obtained by changing altitude. A round tethered balloon is unstable in any significant wind. A kite balloon is streamlined to make it stable in strong winds. Today, the majority of manned balloon flights are recreational, whereas unmanned and usually free-flying balloons are widely used for meteorological measurement. Kites are aircraft that are tethered to some other object (fixed or mobile) or other means that maintain tension in the"