Meteorology

Ten generic-module questions: clouds, fog, fronts and theoretical winds.

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Clouds and fog

Prefixes: cirro, high cloud; alto, middle cloud; strato, low cloud. Cumulus and cumulonimbus are of vertical development.

Advection: moist air over a cold surface, the typical sea fog. Radiation: cooling at night on land.

Theoretical winds

Euler: gradient alone. Geostrophic: gradient and Coriolis, parallel to the isobars. Cyclostrophic: centrifugal force dominates. Antitriptic: friction dominates.

Activities

• Weather visualsClouds, fog, isobars, breezes and sea state.
• Read the skyCheck the sky, barometer and wind. What is coming?

Questions in this unit

• When cold air advances and pushes the warm air ahead of it we have:
• In warm fronts…
• The pressure difference between two consecutive isobars per unit distance tells us about:
• On relative humidity, mark the CORRECT statement.
• An occluded front is one where:
• What weather is usually associated with a depression just before our boat crosses the warm front in the Northern Hemisphere?
• The horizontal distance between two successive wave crests is called:
• What does the horizontal pressure gradient at a point tell us?
• The current in the Strait of Gibraltar generally runs:
• Mark all the components considered in Eulerian winds.
• By height, cirrocumulus are classed as:
• What is the main origin of waves?
• What can we learn with a psychrometer and its tables on board?
• The wind coming from the European continent, blowing from the NE and typical of the Balearic Islands, is called:
• In an air mass, the ratio between the vapour pressure actually present and the maximum possible at a given temperature is:
• Fog is naturally dispersed, as a rule, by:
• How many thermometers, and of what type, make up a psychrometer?
• One of a wave’s characteristic parameters is the period, defined as:
• The boundary between an advancing cold air mass and the warmer air it displaces is called:
• On isobars, mark the CORRECT statement.
• Which two main factors can disperse fog?
• On absolute humidity, mark the INCORRECT statement.
• The period of a wave is:
• The Portugal current runs along the Spanish Atlantic coast heading:
• Altocumulus belong to:
• Geostrophic wind adds to Eulerian wind:
• The wind in which centrifugal force balances the pressure gradient is called:
• Differences in sea water temperature and salinity between areas and depths create a current called:
• In low clouds (stratus) the base height is:
• With a low over North Africa and a high over northern Spain, the resulting wind is called:
• On the horizontal pressure gradient, which statement is false?
• Eulerian wind is:
• A trough (vaguada) is:
• The sea currents that can reach the greatest strength are:
• In the Strait of Gibraltar…
• What characterises an anticyclone in the Northern Hemisphere?
• Stratocumulus are:
• Orographic fog forms…
• We see a depression with isobars 50 miles apart. 24 hours later the same isobars are 25 miles apart. What has happened to the wind?
• What weather goes with a depression?
• Most surface currents in the open ocean, caused directly by the wind, are called:
• The wind in which friction dominates and the other parameters are ignored is called:
• Condensation in a warm, moist air mass passing over a cold surface creates:
• A front where cold air pushes and displaces warm air is:
• With a psychrometer, what can we forecast?
• The horizontal pressure gradient is the difference between two isobars at the same height 60 miles apart. What is it useful for?
• By height, cirrus clouds are:
• Which wave feature is the time between two crests passing the same point?
• What is the main cause of density currents?
• At sea, with calm wind and regular waves whose wavelength far exceeds their height, with rounded crests that do not break, we are sailing in:
• How can relative humidity be defined?
• The wind resulting from the horizontal pressure gradient and the Coriolis force is called:
• The dew point is:
• If a cold front passes over us:
• Absolute humidity…
• If isobars are very close together…
• A front is:
• What are isobars?
• Currents in the Strait of Gibraltar. The strait has strong currents: which is true?
• “Relative humidity” is…
• What are currents caused by density differences, from differences in temperature and salinity between waters in different places or depths, called?
• What mainly causes wind-drift ocean currents (“de arrastre”)?
• Fog that appears ahead of a warm front, formed as warm rain from nimbostratus evaporates while falling through cold air below, is:
• By the cooling process that forms them, fogs are mainly classed as:
• In a cold occlusion:
• Which clouds, by height, are middle clouds?
• What can we deduce if the isobars on a chart are far apart?
• What is a front called that was warm at first but whose rear has been overtaken by cold air that lifts it?
• What is the length of a wave?
• What causes ocean currents to form?
• What is swell (“mar tendida o de fondo”)?
• When warm air advances and replaces cold air, the contact surface is called:
• The main wave parameters are:
• Absolute humidity is:
• What is a front called that was initially warm but has been reached by cold air that lifts it?
• The Tramontana is a wind found in:
• By origin, ocean currents are classed as:
• Stratocumulus are considered:
• Fog formed when a moist, mild air mass moves over a surface colder than its dew point is called:
• In a depression, if the isobars are very close together there will be:
• The horizontal distance between two consecutive wave crests is called:
• A wind dominated by the pressure-gradient force, with Coriolis negligible, is called:
• When a rising current reaches the condensation level, what forms is:
• When the wet and dry bulbs of a psychrometer read the same:
• In a cold-type occlusion:
• The amount of water vapour in one cubic metre of air is called:
• Gradient currents arise:
• Depending on the fog type, it may clear when:
• The wind that would arise from the horizontal pressure gradient alone is called:
• When two air masses meet, one relatively cold and one relatively warm, what usually forms is:
• Winds called “vendavales” are usually from:
• An occluded front:
• The weather linked to a passing depression is characterised by…
• The horizontal atmospheric pressure gradient…
• Sea currents are classified, by their causes, as…
• From Algeciras to Cabo de Gata…
• A low cloud is one whose base is below…:
• Cold air masses, arctic or polar, on moving to milder latitudes…
• If we are talking of a warm front:
• The “amount of water in the air at a given moment expressed in grams per cubic metre of air” is…
• What phenomenon is the main cause of drift currents?
• As to Dew Point, it is always reached when:
• As to absolute humidity, choose the CORRECT statement.
• In the Canary Islands the general current usually sets:
• The most important currents in the Strait of Gibraltar are
• Fogs formed when a cold air mass moves over warmer water are called:
• Fog can be expected when:
• The horizontal pressure gradient:
• Surface ocean currents circulate in step with the general wind circulation. This is due to:
• The horizontal pressure gradient is:
• Classifying clouds by height, which are high clouds?
• Density or thermohaline currents arise:
• Using the psychrometer aboard we can foresee fog, which could form when:
• The current World Meteorological Organization cloud classification by shape is:
• What clouds form from condensing rising air currents caused by thermal instability?
• A wind in which the pressure gradient is balanced only by the Coriolis deflecting force is called:
• In a depression ahead of the warm front, visibility and precipitation will be:
• As a galerna passes, the wind shifts to:
• When warm air displaces cold air, it is:
• By how they form, frontal fogs are fogs of:
• Regarding ocean currents:
• By how they form:
• A wind running parallel to straight isobars and close to 90% of the real wind is called:
• The galerna is:
• To forecast fog aboard we use the psychrometer, which with psychrometric tables is used to:
• On ocean currents, mark the true option:
• The prevailing direction of the trade winds in the northern hemisphere is:
• Swell (“mar de fondo”) forms waves with:
• Wind sea (“mar de viento”) forms waves with:
• The greater the horizontal pressure gradient:
• On ocean currents, mark the correct option (gradient, drift, thermohaline):
• By altitude, altocumulus clouds are classed as:
• On open-sea waves, mark the correct option:
• On fronts, mark the correct option:
• On wind models, mark the correct option:
• In the northern western Mediterranean, especially the Gulf of Lion, the cold dry NW wind is called:
• On ocean currents, mark the FALSE option:
• On fogs, mark the correct option (frontal, steam, mixing, advection):
• On the horizontal pressure gradient, mark the correct option:
• A sudden, very strong, gusty wind, with or without rain, typical of the Cantabrian Sea, abruptly ending calm hot weather, is called:
• On ocean currents, mark the correct option (density, tide, deep currents):
• The Euler wind:
• On how fogs form, mark the correct option (advection definition):
• On fogs, mark the true option:
• On the horizontal pressure gradient and the slope of isobaric surfaces, mark the correct option:
• Mark the correct option (gradient, geostrophic, Euler, antitriptic winds):
• On waves, mark the correct option (wavelength, height, wind-sea crests, period):
• A western Mediterranean wind, extremely hot in summer and mild in winter, is called:
• The smaller the horizontal pressure gradient:
• Mark the correct option (geostrophic and Coriolis):
• On waves, mark the correct option (energy transfer):
• Advection fogs are due to processes of:
• Mark the correct option on warm and cold fronts:
• In the Gulf of Cádiz, a strong winter south-westerly with lows, rain, gales and poor visibility is generally called:
• Mark the correct option (which wind follows the isobars):
• On how advection fog forms at sea, mark the correct option:
• About clouds, mark the correct option (cumulonimbus):
• On the dew point, mark the correct option:
• What does a set of very closely spaced isobars on a weather chart show?
• About clouds, mark the correct option (stratocumulus):
• Drift currents result from:
• On waves, mark the correct option (period definition):
• About clouds, mark the correct option (classification by height):
• Currents due to temperature and salinity differences between waters in different places or depths are called:
• About the dew point, mark the correct option (saturation):
• Radiation fogs are due to processes of:
• A western Mediterranean wind with low temperatures, dry air, very clear skies and strong gusts is called:
• The density of water vapour in grams per cubic metre is the definition of:
• By how they form, cooling fogs are classed as:
• An ideal wind acted on only by the horizontal pressure gradient is called:
• On waves, mark the correct option (what wind sea is):
• What characterises a cold front as it moves?
• Mark the correct option on the horizontal pressure gradient’s importance:
• Mark the correct option on humidity terms:
• Mark the correct option on radiation, advection and steam fogs:
• On tidal currents, mark the correct option:
• By definition, an isobar is:
• Wave period means:
• On surface isobaric charts, what shows the pressure gradient?
• Waves seen from the coast but generated far away are called:
• The Euler wind has a direction:
• Heading for the Strait of Gibraltar, 3 miles off Cabo de Gata, bearing in mind the Strait current, we should:
• Radiation or land fogs occur when…
• Trade winds are typical of…
• In warm fronts…
• Choose the true answer:
• In port before going to sea we see that pressure has fallen and wind speed is rising:
• If we have an area where closed isobars have a pressure below 1012 millibars, we are in:
• The time, in seconds, between two successive crests passing the same point is called:
• Radiation fogs come from a process of …
• Frontal clouds form:
• Dew point is defined as:
• Choose which type of fog does NOT form by cooling:
• Clouds of vertical development (cumulonimbus) can reach a height of:
• To forecast fog with a psychrometer, we need relative humidity and dew point. For this:
• The horizontal pressure gradient is:
• Not a Mediterranean wind:
• The geostrophic wind is:
• Wave height (H) is defined as:
• Dew point can be defined as:
• Sailing in the Balearics, the wind from the Northwest is called:
• The wind component arising only from the pressure gradient between two air masses is called:
• What are the features of the current affecting the Cantabrian and Galician coasts?
• The horizontal pressure gradient lets us:
• “Relative humidity” is…
• The thin transition zone between advancing warmer air and retreating colder air is called:
• “Swell” (mar de fondo):
• The complex front that forms when a cold front catches a warm front, being faster, is usually called:
• On absolute humidity, mark the INCORRECT statement.
• The geostrophic wind:
• How are stratocumulus classified by height?
• How can we define the dew point?
• On isobars, mark the CORRECT statement.
• The wind resulting from the horizontal pressure gradient and centrifugal force is called:
• The commonest cause of waves is:
• Sailing in the northern hemisphere, what weather do we usually meet crossing a low’s cold front?
• In general, the current off the west coast of Galicia sets:
• On how sea or advection fog disperses, we can generally say that:
• Off Cabo de Palos (Murcia) a south-westerly rises, bringing rain and reaching the coast dry and warm with dust haze. Which wind is it?
• If a weather warning says FOG, visibility will be:
• In winter in the Gulf of Lion, winds causing very bad weather blow from:
• On clouds:
• Altocumulus is:
• The wind moving in a straight line from high to low pressure, at right angles to the isobars, is…:
• In a “warm front” occlusion…
• Cloud formation begins:
• A front is:
• If we talk of stratiform or cumuliform clouds, we are classifying clouds by their…
• On board, you can predict fog forming if you have a…
• Density currents are produced by…
• When moist air passes over a colder surface, the fog formed is:
• The antitriptic wind is:
• What can be deduced if on an isobar map they are very close together?:
• Choose which clouds are, by height, high clouds:
• The parameters defining a wave are: