Cheat sheet - atsc 113 PDF

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Warning: TT: undefined function: 32 Warning: TT: undefined function: 32 Mesoscale Convective Systems: Squall-Line-Wall of thunderstorms right next to each other, often being pushed by a cold front. Bow-echo-A line of thunderstorms is bent into an arc shape by fast winds from behind called the rear i...

Description

Normal Clouds: Convective or Cumuliform Clouds: Look like stack of cotton balls, and are associated with updrafts. Layer Clouds or Stratiform Clouds: Looks like sheets or blankets that can extend hundreds of km horizontally Special Clouds: Clouds in Unstable Air Alo Castellanus: Looks like small castle turrets, are a clue that the atmosphere is becoming unstable (thunderstorms possible later in the day) Billow (K-H wave) Clouds: Indicates wind shear(change of wind speed or direction) and clear air turbulence at aircraft altitudes. Cloud Associated With Strong Winds Across Mountains Lenticular (mountain wave) Clouds: Indicate vertical wind oscillations and possible mountai wave turbulence, updrafts help sailplanes but hurt commercial planes Rotor Clouds: Indicates severe or extreme turbulence at low altitudes. Banner Clouds: Forms on downwind side of mountain peak. Indicates strong turbulence touching the downwind side of a tall, isolated mountain peak. Clouds Formed by Extra Heat, Updrafts or Turbulence Pyrocumulus: Forms over forest fires and volcanoes, the strong heat and moisture can make thunderstorm-Pileus: Forms over fast growing cumulus clouds-Fractus/Scud: Forms in turbulent humid air near the ground. Indicates high humidity and strong winds at low altitude. Clouds Formed by Humans-Fumulus: Water droplet clouds over coolin towers-Contrails: Aircraft condensation tail. Cloud Ceiling: The height above ground level of the lowest cloud base that is below 20,000ft tha is covering more than half the sky Visibility: - Horizontal Visibility: How far away you can see a black object during daytime or how far away yo can see a bright light at night. If visibility is poor, pilots will have difficulty seeing; ground landmarks for navigation, other aircraft or obstacles, the horizon to keep plane level, the runway- Runway Visua Range: How far ahead a pilot can see along a runway centerlineVertical Visibility: The height of the cloud base above ground defines the ceiling altitude. Flight Regulations- Visual Flight Rules(VFR): You can fly mostly by looking out the window, and needs good visibility an stay out of the clouds, by looking you can; navigate, control the aircra and find airports and land on runway. Visual Meteorological Conditions(VMC): Name given to weather that is good enough to fly VFR. When pilots who fly VFR accidently fly into the clouds pilots are not able to determine if the aircraft is right-side up, Pilots lose track o where they are, Psychology is a factor, like panic. Rules for VFR: Can only fly VFR when the ceiling is >3000ft Abv. Ground Level AND Visibili is >5 Statute Miles. Marginal Visual Flight Rules(MVFR): Conditions where VFR is allowed but for which visibility is poo. Rules for MVFR: Ceiling must be between 1000ft & 3000ft, and/or visibility must be between 3&5 SM Instrument Flight Rules(IFR): You can conduct most of the flight by not looking out the window, instead you; navigate usin onboard GPS map displays, control the aircraft by looking at the instruments on your dashboard, get to airports by following instructio and ATC. Rules for IFR: Ceiling can be 80% Factors that affect Surface heating and cooling: Sun angle- lower in polar latitudes, and perpendicular in the equator, heats the ground at different rates. Cloud Cover- unshaded ground surface receives max possible incoming solar radiation. Clouds reduces the amount of incoming solar radiation. Wind Speed- The wind can reduce solar radiative heating effect to some extent, at night wind shea turbulence mixes air from above and near the surface, reducing the radiative cooling effect Arctic Air Outflows: Skiing hazards- Arctic air presents two major hazardous weather conditions to skiers; bitter cold air and outflow winds. Terrain Channelling of winds: Large-scale winds are modified in some way by terrain features. The wind can accelerate when it passes over ridgetops and gets channelled through valleys and gaps in terrain. This channelling can modify wind direction substantially almost always in the along-valley direction. Gap Winds-these usually occur when the large-scale prevailing wind direction is perpendicular to the large mountain range. Such as when cold arctic air approaches the coast mountains, since it is much more dense, the mountain range acts as a barrier, damming the stable cold air behind it. Since there is blockage, conservation of air mass requires it accelerates, so the wind speed for gap winds are around 20-90km/h The Freezing Level: Temperature typically decreases with height, meaning if lower elevation are above freezing, and you go up in elevation, eventually you will cros the freezing level. The rain-snow line is not the same as the freezing level(it is usually 200-300m below the freezing level), this is because the rain snow line is a transition zone as it takes time for snow to melt into rain Density of Newly Fallen Snow: Snow density can be defined as the amount or mass of ice and liquid water per volume, but don’t worry about liquid water, as there are a lot more ice in the snowpack. The effect of conditions on newly-fallen snow: Temperature- Newly fallen snow density increases with increasing temp. For temps close to freezin you can expect higher density snow, partially because it has higher wat content. Snow density decreases with decreasing temp. Wind- As wind speed increases, newly fallen snow density increases. Snow density and ski quality: Low-density snow is easier to ski in than high density snow. The lighter, fluffier snow is easier to push around with your skis. The optimal snow density is 8% total water content. Right-side Up and Upside Down Snow: Right side up snow has higher density snow underlying lower density snow. This occurs when temperature or wind speed decreases during course of storm. A typical right side up storm would be cold front dominate, and as temp decreases following a cold front, the newly falling snow would decrease in density as the storm passes, leading to the right side up snow layer. Great for skiing as its more bouncy, and less prone to storm snow avalanches as the new sno layers are more stable. Upside down snow is higher density snow overlying lower density snow. This occurs with a warm front, temp increase following a warm front, leading to increasing newly fallen snow density with time. The snow is difficult to ski, as the ski tips will dive down under the snow. Makes for bad avalanche conditions, as you’ll have problems with storm-snow avalanches. Snowpack Evolution(Snow metamorphism): Processes that influence the snow crystal size and shape, snow density, snow depth and how well the snow crystals are bonded together. A gradient is a change in property such as temperatu over a distance. There is a vertical temp gradient in the snowpack because of the difference in temp where the snow meets the ground, water vapour moves within the snowpack from warmer to colder temps Further, the speed at which it moves is related to how strong the temp gradient is. Since the bottom of the snowpack is on average warmer tha the top, water vapour within the snowpack generally travels upwards. The higher the temp, the higher the vapour pressure and vice versa. Snow Crystal: Faceted Crystals- produced when a strong vertical temp gradient exists(when the snow surface is very cold). The water vapour is moving quickly, and crystal growth happens quickly. There is large space in between snow crystals. Occurs more frequently in colder, continenta climates with drier and clearer weather and shallower snowpacks. Rounded Crystals- are produced when temperature gradients are weak, water vapour moves slowly and crystal growth happens slowly. Typical rounding occurs when the vertical temperature gradient in the snowpac is less than 1C per 10cm in depth. Rounding occurs more often in warmer, wetter, coastal climates, where cloud cover is more frequent, and the snowpack is deeper and tightly packed crystals. Stable & Unstable Snowpacks: Snow Pits- gives information about snow layers inside the snowpack, and are typically 1-2 metres deep. Analysis include layer identification, snow crystal type, hardness tests, and stability tests Hand Hardness Test- Applying light pressure to each snowpack layer. Th hardness levels from softest to hardest are, fist, four fingers, one finger pencil and knife. Stable and unstable Snowpacks- It’s the layering of multiple layers that determines if the whole snowpack is stable or unstable. The stronger/harder/denser/more cohesive layer on top of a weaker/softer/less dense/less cohesive layer is an unstable configuration. A layer with four finger hardness may be considered wea if it’s below a one-finger hardness (Strong over weak), but can be considered strong if its below a fist hardness layer(Weak/Strong) Layers like facets and buried surface hoars are particularly dangers, as they are weak compared to any other. Snow Climates: Coastal snow climate (Frequent snowfall, high density fallen snow, warm temps, coastal location, deep snowpack, most avalanches occur during or soon after storms, infrequent persistent weak layers in snowpack, lower avalanche danger) Tends to be on Western side of continents in Northern Hemisphere, moisture from ocean. i.e The Coast Mountains. Transitional Snow Climate (Moderate amounts of snow and density, frequent snowfall, snowpack of moderate depth, some storm snow avalanches, Infrequent persistent weak layers, lower avalanche danger) Typically just inland from the coast, so that storms will have already precipitated some of their moisture over upstream mountain ranges i.e The northern Japanese Alps Continental Snow Climate (Low snowfall, Low density snow, cold temps, inland location far from coast, shallow snowpack, persistent weak layers, higher avalanche danger) Far inland from moisture source. i.e The Rockies Aspect Effect: South facing slopes receive a more direct sun angle, and north facing slopes get a less direct angle.

On Southerly aspects, the snow can get crusty as the surface is melted an then refrozen. On Northerly aspects in the winter, even when the air tem measured at 2 m above ground level is above freezing, the snow surface can remain below freezing, thus northerly aspects are the best aspects to find preserved powder during sunny periods. The downside to the consistently colder snow surface temps is that faceting and surface hoars are most likely to be found. Surface Hoar: essentially the frozen version o dew, it is produced by deposition onto the snow surface, when the air temp falls below the frostpoint temp. The outcome is a formation of ice crystals on the top of the snow surface. Conditions to form (Clear skies, calm winds, strong temp inversion, continually forms on northerly aspect as they cool radiatively with little to no heating from sun, flat or open surface) Hazards- Surface hoars can lead to avalanches, once its buried by subsequent snowfall, the hoar acts as a weak layer within the snowpack. the surface hoar is uniform over a large area, larger slab avalanches are likely. The gradual accumulation of snow on top may be enough to trigge an avalanche. Avalanches: An avalanche can be simply defined as a mass of snow that moves quickly down a mountain slope. Loose-Snow Avalance- Made up of surface or near surface snow that is not well bonded, begins at a single point, and fans out as it falls. Doesn’t do majo structural damage but can still bury someone. Wet Sluff AvalancheCaused by snowmelt form strong solar radiation, or rainfall, the small amount of liquid water content gives the snow a small amount of strengt Slab Avalanches- When a layer in the snowpack slides down the slope as cohesive, bonded layer. Hard slabs are a result of high density, well bonded snow. Soft slabs are comprised of low density snow that has mor bonding than newly fallen snow. Snow Habits: As temp decreases below 0C, snow crystals changes from flat plates, to long columns or needles, back to plates again, and then to columns and plates. As humidity increases, the snow crystals then to get bigger, and tend to get more branches or dendrites on them Optimal Ski Pistes: Recreational Ski Pistes Groomed compacted run (Safe, smooth, even, durable, interesting in thei terrain, visually attractive, good grip) Racing Ski Pistes- compact, steep. Reinforce snowpack hardness- Pistes are maintained immediately following closing, hardening process happens fastest if snow temp is as close to 0 as possible, grooming machines, skis or feet to compact the surface, using man made snow is higher in density, water injection to help snow freeze, using chemicals to drop the snow’s melting point Resort Snow Surface Conditions: Hard Packed- when it hasn’t snowed for a few days and the snow surface has since been compressed. Soft Packed-when freshly fallen snow has been somewhat compressed, and is nice to ski on Powder- substantial snowfall of anywhere between 10cm and 50cm, or by wind loading, which is loose snow blown into gullies. Dry-no liquid water the snowpack. Moist- Snowpack moisture is influenced by location and warm temps. Melting- The snow starts to melt at 0C and increases friction Slush-Find slush conditions during springtime in the afternoon, whole top layer is melting. Snow conditions are important- Helps you identify the best times to go skiing. Different waxes are used for different snow and a temps, so understanding snow conditions is a first step to understanding the application of wax. SAILING: Wave Formation: Three main factors tha affect wave formation: Wind velocity, fetch and duration. Wind velocity is the speed of the wind, fetch is the distance over the water that the wind can blow uninterrupted, and duration is the amount of time the wind blows over that patch of water. The greater the wind velocity, the longer the fetch, and the longer the wind blows over that patch of water, the more energy converted to waves, and the bigger the waves. It takes all three factors acting together to create big waves. When wind moves across the water’s surface, it creates frictional drag. It is a force that acts against the relative motion of one fluid with respect to another fluid. The texture of the ocean’s surface can influence the way the wind moves over water and the amount of friction or drag produce Wave Characteristics: Crest=highest point of the wave; wavelength=distance from one crest to the next; period = time of one full wavelength to pass a given point; amplitude=distance from the centre of wave to bottom of trough; wave steepness=ratio of wave height to wavelength wave train= as waves disperse from the storm, they settle into groups of different wave sizes and velocities continuously moving away from the source; group velocity= The speed at which one group of waves travels across the water; phase velocity= The apparent speed of each individual wave in the group Wind Generated Waves: Waves are a result of wind disturbing the ocean’s surface. Swell- waves formed by distant storms, and are gravity waves originating from heavy winds and are capable of travelling long distances with little energy. They have lower wave heights, longer wavelengths, less susceptible to decay from surface winds. Series of waves generated at a distance;well-sorted. Rogue Waves- Very large waves that form due to wave interference, when two waves run into each other, and they add up (constructive interference) or cancel out (destructive interference) Rogue waves are a result of constructive interference with unusually high waves Tsunamis- Very long waves resulting from seismic events. Wavelengths can be >200km with long wave periods. They may start small out at sea, but when they meet the continental shelf, their wave height increases dramatically Breaking Waves: as waves approach shore, bottom of wave meets ocean floor; waves drag across bottom, and front waves slow down – wavelength reduced. Following waves begin to build up behind, and as wavelengths shorten, energy transfers up → wave height. When h/l > 1:7, breaks.

Local tides and direction that swell approaches affects breaking; waves reaching shallow water break first. 3 types of wave: spilling breakers, plunging breakers, surging breakers. Spilling: occur as waves travel across gently sloping bottom. Plunging: moderate to steep bottoms, crest falls as well defined curl. Surging: long wave period, low amplitude, moderately steep – buidls up then slides rapidly up the beach. Forecasting swell: swell direction, wave height and period, local conditions (wide/tide) all that is necessary. Swell direction: forecast in degrees Wave Height and Period: “swell of 6ft at 15 seconds” = wave height 6ft, period 15 seconds. At beach, longer period means more time for wave to build. Local winds: onshore and offshore. Onshore winds blow from ocean to shore, and creates chop on incoming swell → reduces steepness. Offshore the reverse – slow speed of waves. Tide: - beach steepness. Swell refraction: if part of wave hits shallow water first – irregular breakers form. Swell decay: steeper waves with shorter wave periods decay more rapidly. Beaufort Scale: 0-12 scale, 0 is calm, 8 is gale, 10+ is storm. Wind Circulations: Hadley Cell: refer to image. Sunlight heats air more in tropics than poles, therefore temp gradient between equator and poles. Warmer air near equator rises and creates region of heavy rain and thunderstorms called the ITCZ (intertropical convergence Zone)/Doldrums. Horizontal winds calm here. Warm air rises to top of troposphere, and spreads to poles, but only gets as far as 30 degree latitude before turned to east because of coriolis effect. As air accumulates here, pressure aloft increases, therefore air forced down – air accumulates here and called subtropical high pressure zone. Low winds here, hard to sail. Descending air is very dry, and as surface air blows back to equator it is turned to the right in N hemisphere, left in S. Hemisphere, because Coriolis → resulting in trade winds. Mid-latitude cyclones – at mid latitudes there is not strong vertical circulation cell, instead, large horizontally swirling low/high pressure systems. High pressure called anticyclones, low pressure called extratropical cyclones. Corioles effect causes winds rotating counterclockwise around lows in N hemisphere, and clockwise around highs. Circulations are superimposed by a general west to east movement of all the air at mid latitudes – latitude band of westerlies tend to be strong in southern hemi. Polar Cell: occur between 60 degree latitude and poles. Air movements here weaker compared to Hadley cells. Cool air meets the warmer mid latitude air near 60th parallel, where it rises. Known as polar front. Jet Stream: form where air masses of different temps converge. Greater temp diff, strong winds. Jet stream near 60 latitude called polar jet stream, subtropical jet stream near poleward limit of Hadley cell. Flow in troposphere, predominantly westerly. Have strong influence on local weather since responsible for pushing masses of warm and cold air around – mid latitude cyclones created on east side of jet stream troughs. Flow pattern like wave – troughs and ridges for areas of high and low pressure. Walker Cell: thermal energy transported longitudinally across equatorial pacific known as walker cell. Driven by temp and pressure gradients. High pressure forms over cooler pacific waters (cool air = slow particles, → densely packed → higher pressure). Low pressure forms over eastern Pacific. Play a role in trade winds. These winds push cooler water from eastern pacific across equator to west pacific, warming as it goes – warm air over west pacific waters rises, losing moisture. Dryer air travels back, creating loop. Air flow creates similar ocean current – as water pushed from E to W, deep cooler water rises to surface to fill gap – called upwelling. El Nino: 3 states: el nino, la nina, neutral. Neutral = normal walker cell, el nino is warmer phase, la nina is cooler phase. El nino occurs when trade winds weaken – imagine water bouncing back towards you – warm water from western pacific surges towards east, and upwelling of cooler water along eastern pacific slows/stops. La nina phase occurs when trade winds stronger than normal, instead causing increased upwelling of cool waters along eastern pacific, more cold water being pushed further across pacific. Ocean Currents Worldwide Cu...