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Bronze Badge. Meteorology Syllabus. Richard Lovett - Brief CV Royal Navy Meteorologist later specialising in underwater warfare and submarine operations Met forecaster at Fleet Weather Centre, Northwood RNAS Culdrose and Portland
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Bronze Badge Meteorology Syllabus
Richard Lovett - Brief CV Royal Navy Meteorologist later specialising in underwater warfare and submarine operations Met forecaster at Fleet Weather Centre, Northwood RNAS Culdrose and Portland Senior Met Officer HMS Daedalus HMS Endurance Hong Kong Naples Senior Instructor at RN School of Meteorology and Oceanography, RNAS Culdrose. Then Maritime Tactical Course, HMS Dryad, and the world of underwater warfare and submarine operations. Responsible for advising MOD on future submarine operational requirements , sonar systems and torpedoes.
Bronze Badge Meteorology Application of elementary aeronautical meteorology Obtaining and use of meteorological information
Circulation of the Atmosphere • Air Masses • Pressure systems • Fronts • Wind and pressure • Lapse rate - Stability and Instability
QUESTION 18. • Due to a high pressure system the prevailing wind across the • UK is from the south west on a summers day. • What name best describes this wind? • Tropical maritime. (Correct!) • Tropical continental. • Polar maritime. • D. Polar continental.
QUESTION 63. • What would be a typical characteristic of a • Tropical Continental air mass in winter? • Warm and fairly dry. (Correct!) • Warm and moist with low cloud, rain/drizzle. • Cool and moist perhaps with hail and thunder. • D. Very cold and dry.
QUESTION 69. What name is given to an air mass that originated from Greenland? A. Polar Continental. B. Tropical Maritime. C. Tropical Continental. D. Polar Maritime. (Correct!) QUESTION 70. What name is given to an air mass that originated from Africa? A. Polar Continental. B. Polar Maritime. C. Tropical Maritime. D. Tropical Continental. (Correct!)
QUESTION 45 • What conditions are usually associated with warm dry air • from the continent flowing over the UK in the summer? • Convective cloud, showers and thunderstorms. • Stratus, sea fog and drizzle. • Warm with clear skies. • D. Warm with hazy weather. (Correct!)
Depressions Low pressure Circulation is anticlockwise in northern hemisphere Often associated with fronts and precipitation Air flows inward towards the centre and then rises. Often fast moving with rapid development Wind strength less than geostrophic for same isobaric spacing
Anticyclones High pressure Clockwise circulation in northern hemisphere Generally fine weather in summer but anticyclonic gloom is typical in winter Air subsides over centre causing warming and subsequent inversion Inversion can trap pollution and cause poor visibility with haze Wind strength greater than geostrophic for same isobaric spacing
Coriolis Effect Newtons Laws of Motion applied to a rotating frame of reference Objects in motion are deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere due to the rotation of the earth.
geostrophic wind theoretical wind that would result from an exact balance between the Coriolis effect and the pressure gradient force. This condition is called geostrophic balance. The geostrophic wind is directed parallel to isobars (lines of constant pressure at a given height). This balance seldom holds exactly in nature. The true wind almost always differs from the geostrophic wind due to other forces such as friction from the ground or the centrifugal force from curved fluid flow. Thus, the actual wind would equal the geostrophic wind only if there were no friction and the isobars were perfectly straight. Despite this, much of the atmosphere outside the tropics is close to geostrophic flow much of the time and it is a valuable first approximation.
Relationship between Geostrophic and Surface Wind Surface wind backed 30 degrees from geostrophic Surface wind strength about 1/3 of geostrophic over land (2/3 over sea) These are approximations and depend on friction effects of land surface
QUESTION 3 • What does ‘Buys Ballots’ law state of the northern hemisphere? • If you stand with your back to the wind the low is on your left (Correct!) • . • If you stand with your back to the wind the low is on your right. • Low pressure systems rotate clockwise when viewed from above. • D. Temperature decreases with height at a rate of 1.7 degrees per 1000 ft.
QUESTION 16 • What are the effects of diurnal variation on the soaring day? • The wind increases at the start of the day and • decreases at the end of the day. • The wind veers and increases at the start of the day and backs and • decreases at the end of the day. (Correct!) • The wind backs and increases at the start of the day and • veers and decreases at the end of the day. • The wind veers and decreases at the start of the day and • backs and increases at the end of the day.
anabatic wind a wind which blows up a steep slope or mountain side, driven by heating of the slope through insolation. katabatic wind the technical name for a drainage wind, a wind that carries high density air from a higher elevation down a slope under the force of gravity. Such winds are sometimes also called fall winds. Not all downslope winds are katabatic. For instance, winds such as the Foen, Chinook or Bergwind, are rain shadow winds where air driven upslope on the windward side of a mountain range drops its moisture and descends leeward drier and warmer. Katabatic winds can rush down elevated slopes at hurricane speeds, but most are not that intense and many are on the order of 10 knots or less. Examples of true katabatic winds include the Mistral in the Mediterranean, the Bora (or Bura) in the Adriatic, the Santa Ana in southern California.
Advection the transport of some property of the atmosphere or ocean, such as heat, humidity or salinity. Advection fog is caused by warm moist air flowing over a cold surface Orographic lift occurs when an air mass is forced from a low elevation to a higher elevation as it moves over rising terrain Radiation Loss of heat from ground at night which results in cooling of low level air and fog formation
Rotor cloud is a closed, vertical circulation that develops in the lee of high mountain barriers, or in the valley between two mountain ranges, when conditions are appropriate. The rotor is a form of lee eddy The Helm Cloud and Helm Bar of Cross Fell, northern Pennines
Fog visibility is less than 1 km Mist visibility is between 1 km and 2 km and relative humidity is above 95% Haze Poor visibility when RH is below 95%
dew point the temperature to which a given parcel of air must be cooled, at constant barometric pressure, for water vapour to condense into water. The condensed water is called dew. The dew point is a saturation point. When the dew point temperature falls below freezing it is often called the frost point, as the water vapour no longer creates dew but instead creates frost or hoar frost by deposition.
Hail Ice particles from thunderstorms (Cumulonimbus clouds) These are formed by successive lifting and falling of the particles which acquire layers of ice until they are heavy enough to fall to the ground. As they are lifted above the freezing level they come into contact with supercooled water droplets which freeze on contact.
There are two types of lapse rate: • Environmental lapse rate - the actual change of temperature with altitude for the stationary atmosphere (i.e. the temperature gradient) • An inversion sometimes occurs with anticyclones where the temperature is constant or even increases with height. • The adiabatic lapse rates – which refer to the change in temperature of a mass of air as it moves upwards. There are two adiabatic rates: • Dry adiabatic lapse rate • Saturated adiabatic lapse rate
International Standard Atmosphere (ISA) a temperature lapse rate of 1.98 °C per 1,000 Ft) from sea level to 11 km (36,090 ft). From 11 km (36,090 ft) up to 20 km (65,620 ft), the constant temperature is −56.5 °C
dry adiabatic lapse rate(DALR) 3.05 °C per 1,000 ft saturated adiabatic lapse rate(SALR) 1.51 °C per 1,000 ft
QUESTION 24. • What is a cause of temperature inversion? • Descending air warming due to compression and resting on the cooler air mass beneath. (Correct!) • Pollution in the lower atmosphere reflecting the suns energy. • Uneven heating of the atmosphere due to instability • D. Uneven heating of the atmosphere due to stability.
QUESTION 13 • What effect in general, does a building high pressure system • have on the level of an inversion? • The level rises as the high pressure system approaches. • The level remains the same, however, the dew point does rise above it. • The level falls slowly as the high pressure system approaches. (Correct!) • D. There is no effect on the inversion, however, the cloud base will lower.
QUESTION 28. • What is the approximate rate of change of • temperature with height for the dry adiabatic lapse rate? • 3 degrees Celsius loss per 1000 feet height gain. (Correct!) • 2 degrees Celsius loss per 1000 feet height gain. • 1.5 degrees Celsius loss per 1000 feet height gain. • D. 1 degree Celsius loss per 1000 feet height gain.
QUESTION 29. • When an air mass rises it cools at a given rate. • Cooler air cannot hold as much water vapour as warmer air • and therefore it eventually becomes saturated. What is this • point called, and what happens there? • The saturated lapse point, and cloud vertical development starts here. • The dew point, and cloud vertical development stops here. • The saturated lapse point, and cloud vertical development stops here. • D. The dew point, and cloud vertical development starts here. (Correct!)
QUESTION 31. • What is meant by the term ‘stable air mass’? • The pressure is high, and therefore no thermal activity will be present. • The environmental lapse rate is less than the dry adiabatic lapse rate. • (Correct!) • The air mass is dry, therefore no thermals or cumulus cloud will form. • D. The environmental lapse rate is greater than the dry adiabatic lapse rate.
QUESTION 37. • What is the approximate rate of change of temperature with • height for the saturated adiabatic lapse rate? • 3 degrees Celsius loss per 1000 feet height gain. • 2 degrees Celsius loss per 1000 feet height gain • 1.5 degrees Celsius loss per 1000 feet height gain (Correct!) • D. 1 degree Celsius loss per 1000 feet height gain.
QUESTION 42. • What is the name given to the point at which water • vapour condenses, and what is the required humidity? • The dew point and can occur at any percentage saturation. • The saturation level and can occur above 90% saturation. • The dew point and requires 100% saturation. (Correct!) • D. The evaporation point and requires 100% saturation.
QUESTION 46. • Which of the following is the most accurate definition • of the adiabatic lapse rate? • The rate of change of temperature due to expansion with increasing height, • taking into account the moisture content, i.e. dry or saturated. (Correct!) • The rate of change of temperature with increasing height. • The rate of change of pressure with height, taking into account the moisture content, • i.e. dry or saturated. • D. The rate of change of pressure with height, taking into account air temperature.
QUESTION 47. • The surface temperature is 20 degrees and the trigger • temperature is 24 degrees centigrade. Assuming the • environmental lapse rate 2 degrees, the dry adiabatic lapse • rate is 3 degrees, what height will the thermal go to? • 2000 feet. • 3000 feet. • 4000 feet. (Correct!) • D. 5000 feet.
QUESTION 57. • What are the values of the dry adiabatic lapse rate (DALR) • and saturated adiabatic lapse rate (SALR). • DALR = 3 C per 1000 ft, SALR = 2 C per 1000 ft. • DALR = 3 F per 1000 ft, SALR = 2 F per 1000 ft. • DALR = 3 C per 100 ft, SALR = 1.5 C per 100 ft. (Correct!) • D. DALR = 3 C per 1000 ft, SALR = 1.5 C per 1000 ft.
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