Importance of Aviation Weather
Importance of Aviation Weather
Even novice pilots understand that weather affects a plane in flight very differently than it affects a car driving down the freeway. Although weather conditions can compromise your safety both in the air and on the road, the stakes are higher in flight because you can’t pull over to the shoulder if the severity of weather exceeds your abilities. To better understand the forces that weather exerts on planes, it’s important to realize that the atmosphere is not empty space. Heat from the sun and friction from the earth’s surface act upon the gases and water in the air, creating a variety of weather conditions.
A number of factors—wind, cloud layers, temperature, dew point, barometric pressure, and visibility—affect your Flight Simulator experience. You’ve probably heard your local weather forecaster use these terms, but as a pilot, it’s important that you understand their precise meanings.
Wind
Wind is one of the basic weather factors affecting flight. Depending on its severity, wind can be a nuisance—pushing you off course by affecting your heading, airspeed, or altitude—or a true hazard, creating dangerous flight conditions. Wind can also make takeoffs and landings more challenging if it’s not aligned with the active runway. And, although it seems basic, remember that if you’re flying into the wind, you’re going to fly slower; flying with the wind will move you along faster.
Friction on the ground acts as a kind of brake on the wind. Weather systems don’t move in a straight line and often rotate, so wind in one area may not be blowing in the same direction as wind in another area nearby. Winds can also change quickly across a weather front. Because there can be dramatic differences between the direction and velocity of the wind on the ground and at high altitude, aviation weather reports include information on both surface winds and winds aloft.
Wind shear refers to situations when the wind direction and speed are shifting rapidly over a short distance. Encountering wind shear on final approach to landing can add unwelcome excitement to your flight. If the wind shifts dramatically from a headwind to a tailwind, for example, you may experience severe downdrafts. Because a plane’s airspeed is already relatively low on approach to landing, wind shear can create a dangerous situation.
You also need to exercise care when taking off or landing in crosswinds, and you’ll need to adjust your navigation if wind coming from one side blows you off track. If you’re flying into a headwind, you’ll need to keep fuel consumption in mind so that your plane doesn’t run out of fuel before reaching your destination.
Knowing the current conditions of winds aloft can help you plan your route and altitude to either take advantage of a tailwind or to avoid the worst of a headwind. Let’s say the wind at an altitude of 15,000 feet is blowing 360 degrees at 15 knots and the wind at 25,000 feet is blowing 320 degrees at 30 knots. Assume for this example that your course for the flight is 340 degrees.
Assuming further that the aircraft you choose to fly performs well at either altitude, you might want to plan your flight for 25,000 feet, since you’ll get a speed boost from a quartering tailwind (a quartering wind comes at you from 45 degrees off your tail or nose). If your course was 160 degrees, you might plan to fly at 15,000 feet to minimize the effect of a quartering headwind.
When using the Real-world weather or Weather themes options in Flight Simulator’s Weather dialog box (an option within the Create a Flight dialog box), surface winds and winds aloft will be set for you. You can set surface winds and winds aloft yourself using the User-defined weather option.
Cloud Types
Even to the most casual observer, scattered, puffy clouds are obviously different than solid overcast conditions. But there’s more to it than simple scenery. Clouds vary in appearance due to the different atmospheric conditions that cause them to form. Understanding the conditions that create certain cloud types helps pilots determine what conditions they may encounter up ahead. Conversely, researching weather conditions ahead of time can give pilots an idea of what kinds of cloud layers to expect during flight.
Stratus
Because the air in which stratus clouds form is relatively stable, stratus layers have a flat, even appearance and cover much of the sky. Although you will likely enjoy a smooth ride in these conditions, visibility is often less clear when the air is stable. Smoke, smog, and moisture can stay suspended in stable air, reducing visibility. (You can use the Visibility setting to determine the visibility distance; the type of cloud formations alone will not affect visibility.).
Stratus clouds can be high and transparent, or low and dark grey. The lowest layers of stratus, nimbostratus clouds, are rain clouds. Higher, less-dense stratus layers can produce rain, but it tends to be more showery than the drizzle produced by low stratus layers.
Cumulus
Cumulus clouds are the puffy, pretty ones.They aren’t, however, always benign. Cumulus clouds form in unstable air, which allows them to have greater vertical development than stratus clouds. Most frequently they have flat bases and lumpy tops, and form below 6,000 feet (1,828 meters). The more unstable the atmosphere, the higher cumulus can build.
Cumulonimbus
Cumulonimbus clouds can tower to greater than 50,000 feet (15,240 meters). Cumulonimbus are the clouds that make thunderstorms.Unstable atmosphere with rapidly rising masses of air creates the conditions necessary for thunder and lightning. Pilots should avoid these hazards whenever possible.
Lightning strikes are actually not the most dangerous aspect of thunderstorms. Severe updrafts in a thunderstorm can overstress an aircraft’s airframe, and violent hailstorms often associated with thunderclouds can cause damage to an aircraft’s skin and windshield.
Squall Lines
Thunderstorms can line up along a weather front, creating a squall line. Aircraft must navigate around squall lines, sometimes taking them hundreds of miles off their intended course. Flight Simulator will create squall lines if they currently exist when you click on the Real-world weather option in the Weather dialog box. If you click on the Weather themes option, you can also select the Squall Line theme. If you want to create your own squall lines, you’ll have to create thunderstorms along a line of weather stations by clicking on the Customize button under the User-defined weather option.
Cirrus
Cirrus clouds are characterized by a wispy appearance and very high altitude. Cirrus are composed of ice crystals. Aircraft don’t often fly at the extreme altitudes at which the cirrus reside.
Cold and Warm Fronts
Cold fronts aren’t necessarily cold. It’s actually just the boundary between a mass of cold air and a mass of warm air in conditions where the cold air is moving in to replace the warm air. In the summer, the “cold” air is just cooler than the warm air and may not seem cold to you at all. Warm fronts are just the opposite; a warm air mass moving in to replace cooler air.
Cold fronts are represented on weather maps such as those that you’ll find in Flight Simulator’s Weather dialog box as a blue line with triangles pointing in the direction the front is moving. Warm fronts are represented by red lines. You will only see fronts depicted on the map when you use Real-world Weather. As a pilot, you need to be aware of how cold and warm fronts affect the conditions you’ll be flying in. The cloud conditions and weather you’ll encounter once the front passes depend on the stability and moisture content of the air mass the front is replacing. You won’t create fronts using the User-defined weather option, but you’ll see fronts (as well as high and low pressure areas) depicted on the weather map when using the Real-world weather option.
Pressure Changes
Barometric pressure is important to pilots for two reasons: it affects how the plane’s altimeter works and it affects the weather. In order to measure how high above sea level your aircraft is, its altimeter is set to local barometric pressure. When an air traffic controller says, “Altimeter is 2992″ she’s saying the local barometric pressure is 29.92 inches of mercury. She’s also telling the pilot to set the Kollsman window of the altimeter to read 2992. The reading in feet or meters on the altimeter is known as pressure altitude.
Dew Point
You really don’t need to care about dew, unless you’re sleeping under your airplane’s wing. But when you’re planning a flight you should care about the dew point—the temperature to which the air must be cooled to reach saturation. The air around us contains invisible moisture known as water vapour. The difference between a location’s temperature and its dew point indicates how well the air can currently hold moisture. Because cool air has a harder time holding moisture than warm air, pilots use this information to determine how likely it is that fog, clouds, or precipitation will form.
The temperature/dew point spread is usually given in terms of a percentage of relative humidity. For example, if the temperature is 72 F (22 C) and the dew point is 52 F (11 C), the relative humidity is 49 percent. Using this example, the air is 49 percent saturated with moisture. When the air is cooled to a point where it reaches 100 percent saturation, the water vapour condenses, forming clouds. If the temperature falls further, water drops form and fall to the ground as rain or, if it’s cold enough, ice or snow. The presence of clouds does not guarantee precipitation, but the presence of precipitation guarantees there are clouds in the area. In Flight Simulator, the Automated Terminal Information Service (ATIS) reports the current temperature and the dew point. The closer the dew point is to the current temperature, the more likely you’re going to encounter clouds. If you’re flying into an area where the temperature is 80 F (29 C) and the dew point is 65 F (18 C), you don’t need to worry about a thick layer of clouds blanketing the area. If the temperature is 65 F and the dew point is 60 F (15 C), watch for clouds.
You can set the temperature and dew point for any temperature layer in Flight Simulator. In practical terms, this means you can create conditions where it is more or less likely that clouds will form (although Precipitation is a separate setting within User-defined weather). Be aware that setting a low cloud layer in Flight Simulator weather will not constitute a layer of fog. To create fog-like conditions, modify the Visibility settings using the User-defined weather option.
Density Altitude
Density altitude is pressure altitude corrected for temperature. When the temperature is high, air is less dense. Density altitude affects aircraft performance: An increase in density altitude corresponds to a decrease in engine power output, propeller efficiency, and aerodynamic lift. Density altitude is normally computed using graphs in the pilot operating handbook for each aircraft, but for simplicity’s sake, just be aware that if the weather is hot, your aircraft’s performance will likely suffer. Turbine engine aircraft and turbocharged reciprocating engines suffer less, but density altitude is still a factor.
About the Author
The author is aviation specialist.
|
|
Royal Wulff Triangle Taper Fly Line TT5F Floating 5 Weight $69.90 Please specify color…. |
|
|
Prism EO Atom Box Kite, Fire $20.99 The EO Atom is the newest and smallest member of our brilliantEO (Expandable Object) series of single-line box kites.The three intersecting planes give it great stability but letyou experiment with a wide range of tumbling tricks.No assembly required and folds flat…. |
|
|
Royal Wulff Triangle Taper Fly Line TTF4F Floating $69.90 Please specify color…. |
|
|
NBA Live 07 $2.24 Elevate Your Game with Hundreds of Freestyle Moves!Product InformationIn an all new season take your game to the next level with NBA LIVE 07. With all-new Total Freestyle Control pull off moves only the pros perform asyou replicate the playing styles of your favorite NBA players. Elevate to therim for an electrifying dunk and bring the crowd to its feet or look to yoursuperstars to shift mome… |
|
|
Apache Havoc $39.99 This software is BRAND NEW. Packaging may differ slightly from the stock photo above. Please click on our logo above to see over 15,000 titles in stock…. |
|
|
Prism Stowaway Parafoil Kite $29.99 Color your place in the sky with this nicely packaged, easy-to-fly new addition to the Prism lineup. The Stowaway Parafoil is a high-flying, indestructible soft kite with a spectacular, flowing tail that’s visible a mile away. It combines the ease of an all-cloth parafoil with the drama of a dragon kite’s long tail. Perfect for travel, there’s nothing to break, nothing to assemble, and it stuffs … |
|
|
Prism Kites EO Atom Box Kite $26.00 The Prism EO Atom Kite is the newest and smallest member of the brilliant EO (Expandable Object) series of single-line box kites. Like the others, it folds flat and pops open ready to fly, no assembly required. The three intersecting planes give it great stability but let you experiment with a wide range of tumbling tricks by slacking the line. The Atom has a nice feature for the occasional unplan… |
|
|
White River Fly Shop Tri Fly Rod Tube -9′ 2-Piece Rod – Line/term/acc/boats $27.99 Triangular-shaped rod tubes like the White River Fly Shop Tri Fly Rod Tubes provide benefits not found in traditional round rod tubes. Not only does the Tri Fly Rod Tube design provide virtual crush-proof protection, but the shape also prevents the rod case from rolling around. Built tough from rugged 1000 denier nylon water-repellent material with reinforced seams, the protective foam padding on top and anti-scuff pad on the bottom provide enough protection to give even flying anglers the peace of mind that comes from knowing your rods are well protected. Imported. Color: Tan. Features: Rugged 1000 denier nylon water-repellent material with reinforced seams Protective foam padding on bottom Triangle shape prevents case from rolling around Carrying handle and adjustable shoulder strap Anti-scuff pad on bottom protects case Triangular-shaped rod tubes like the White River Fly Shop Tri Fly Rod Tubes provide benefits not found in traditional round rod tubes. Not only does the Tri Fly Rod Tube design provide virtual crush-proof protection, but the shape also prevents the r |
|
|
Brocard Triangle $79.66 High Quality Content by WIKIPEDIA articles In geometry, the Brocard triangle of a triangle is a triangle formed by the intersection of line from a vertex to its corresponding Brocard point and a line from another vertex to its corresponding Brocard point and the other two points constructed using different combinations of vertices and Brocard points. This triangle is also called the first Brocard triangle, as further triangles can be formed be forming the Brocard triangle of the Brocard triangle and continuing this pattern. The Brocard triangle is inscribed in the Brocard circle. It is named for Henri Brocard. Author: Surhone, Lambert M./ Tennoe, Mariam T./ Henssonow, Susan F. Binding Type: Paperback Number of Pages: 110 Publication Date: 2010/08/16 Language: English Dimensions: 6.00 x 9.02 x 0.26 inches |
|
|
Big Agnes Triangle Gear Loft $22 DECENT FEATURES of the Big Agnes Triangle Gear Loft Triangle Loft-fits: Fly Creek UL 1 – Seedhouse 1 and 2 – Seedhouse SL 1 – 2 and 3 – String Ridge 2 |
|
|
RIO MainStream Saltwater Fly Line – WF12F – Line/term/acc/boats $39.95 RIO’s high-performing MainStream Saltwater Fly Line is an all-purpose saltwater fly line perfectly suited for fly fishers fishing in temperate-to-tropical conditions for multiple species. This weight-forward floating fly line features a hard tropical coating that will not soften in the harsh tropical heat. RIO’s MainStream Saltwater Fly Line is designed similar to the RIO Clouser line where a reverse compound taper and bullet front taper allows anglers to effortlessly turn over big, heavy flies into the wind. Length: 90′. Color: Light Blue. RIO’s high-performing MainStream Saltwater Fly Line is an all-purpose saltwater fly line perfectly suited for fly fishers fishing in temperate-to-tropical conditions for multiple species. This weight-forward floating fly line features a hard tropical |
