ELEMENTI DI METEOROLOGIA PER COMITATI DI...

ELEMENTI DI METEOROLOGIA PER COMITATI DI REGATA

Alessandro Pezzoli, PhD FRGS AFRIN PMP Professore Aggregato Weather Risk Management

Laurea Magistrale Economia dell’Ambiente, della Cultura e del Territorio – Università di Torino

Milano, 30 Settembre 2017

Meteorologia e Comitati di Regata

• Preparazione e organizzazione della regata

• Gestione della regata (con particolare attenzione alla sicurezza oltre che al regolare svolgimento della regata stessa)

• Gestione delle proteste (nel post-regata, per i Comitati delle Proteste è spesso importante stabilire, nei fatti accertati, le condizioni meteo-marine verificatesi durante l’incidente… Utile il Rapporto di Regata fornito dal CdR al CdP)

Meteorologia e Regolamento di Regata (1)


Jury Policies: sect. B.6 - Redress

Meteorologia e WS Race Management Manual (1)

Meteorology: la parola viene trovata 8 volte nel documento compreso l’indice

Meteorologia e WS Race Management Manual (2)

Weather: la parola viene trovata 30 volte nel documento compreso l’indice

Meteorologia e Linee Guida CdR (2)

Meteorologia Fisica Meteorologia Dinamica

Modellistica per la previsione meteorologica

Carte sinottiche (area grande)

Carte a meso-scala (area medio-piccola)

Meteorologia operativa

Misura meteorologica

Real-Time Statistica Climatologia

Bollettino Meteorologico

Quindi…

La previsione meteorologica ha un grado di incertezza (errore possibile) ed il velista deve interagire correttamente con il bollettino di previsione

Bisogna prestare ATTENZIONE alla meteorologia e alla sua influenza sulla regata anche per percorsi brevi

ma non si deve essere scettici…

Un salto di vento a SINISTRA in partenza influenza tutta la regata (devo andare a sinistra partendo sottovento mure a dritta oppure sopravento mure a sinistra…)

Cosa devo fare?

Cosa devo fare (prima della regata)???

La direzione probabile del vento di gradiente può essere ricavata da:

1) Previsione meteorologica dalle stazioni locali

2) Previsione meteorologica pre-registrata ed inviata via telefono (Météo-France)

3) Previsione meteorologica e carte meteorologiche sinottiche inviate via fax

4) Previsioni meteorologiche emesse dai canali televisivi

5) Previsioni meteorologiche emesse dai canali radio

Valutare la tipologia di massa d’aria:

1) Instabile: probabilmente rinforza? Rinforzo con raffiche? Precipitazioni e/o temporali?

2) Stabile: rinforza? Quando l’inversione si interromperà (di mattino o di pomeriggio)? Ci sarà nebbia o cattiva visibilità?

Analizzo il “timing” del passaggio dei fronti ed identifico i tipi di nubi che si possono generare in queste condizioni


Se regato in prossimità della costa:

1) Studio il contorno della costa dalle carte topografiche

2) Identifico: scogliere

3) Identifico: promontori

4) Identifico: valli

5) Identifico: isole (importanti quando il flusso d’aria è stabile)

6) Identifico: baie


Cerco di identificare i possibili “shift” del vento:

1) Shift del vento dovuto al passaggio terra-mare e viceversa

2) Raffiche sopra le scogliere

3) Curvature generate dalle isole e dai promontori

4) Giornata di “sea breeze”? Lo “shift” sarà costante e regolare

5) Flusso nelle baie


Studio la possibile marea:

1) Studio lo stato della marea durante la regata

2) Analizzo la corrente di marea nel campo di regata ed in prossimità della zona costiera

3) Valuto la corrente di marea in prossimità degli estuari e delle baie


Se non sei pratico della marea della zona ricordati di segnarti l’ora dell’alta marea. Dopo due ore dall’alta marea ricordati di non navigare troppo sotto

costa (si potrebbero avere problemi)

2) Analizzo la direzione media del vento (e la velocità). Utilizzo un anemometro a mano

3) Identifico la direzione del vento e cerco di valutare gli “shift”

4) Cerco dei punti cospicui per valutare lo “shift” del vento e la sua tipologia (“shift” frontale, “shift” di brezza…)

5) Valuto la posizione della linea di partenza rispetto alla direzione del vento

6) Analizzo le oscillazioni della direzione del vento rispetto alla linea di partenza

Cosa devo fare (sul posto=“now-casting”=gestione della regata)???

7) Dai 3’ ai 5’ prima della partenza decido il lato in funzione del primo “shift”

1) Valuto se la giornata si presenta con le caratteristiche meteorologiche previste dal bollettino meteorologico (giornata di “sea breeze”, giornata con passaggio di fronti…)

Fronti e masse d’aria

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Fronts and Air masses

• Air mass types and sources

• Frontal types

• Frontal structure in 3-D

27

Fronts and Air masses (cont.) • Air mass types

– Four general categories: • P Polar source (also A for Arctic source) • T Tropical source • c continental (land regions) • m maritime (ocean regions)

• Source regions – Generally flat and uniform composition – Light surface winds – Places dominated by high pressure

• Arctic plains (ice/snow covered) • Subtropical oceans • Desert regions

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Fronts and Air masses (cont.) • Air masses of North America:

(1) cP and cA Continental Polar and Continental Arctic Cold (very cold in winter) and dry, stable conditions. (2) mP Maritime Polar Cool, moist and somewhat unstable. Forms in polar regions, then moves over oceans. (3) mT Maritime Tropical Very warm and moist. Forms over the eastern Pacific and the Caribbean sea and Gulf of Mexico. (4) cT Continental Tropical Hot, dry, and unstable conditions. Forms over northern Mexico and the southwestern U.S. during the summer.

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Air mass source regions

mP

mT

mA

cA

cT

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Fronts and Air masses (cont.) • A front is a transition zone between air masses of different

densities.

• Frontal types:

– Cold front

• Zone where colder air is replacing warmer air

– Warm front

• Zone where warmer air is replacing a retreating colder air mass.

– Stationary front

• Zone that has little or no movement.

– Occlusions • 2 types: Warm and Cold • Occur during mature phase of storm development

32

Cold front structure

33

Warm front structure

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3-D Frontal Structure

Typical sequence of weather associated with a warm front

Front approching As it passes In warm sector

wind increases&backs veers direction steady

cloud sequence of Ci, Cs, As, St, Ns Ns St, Sc

rain become heavier&more continuous stops or turn to drizzle light rain

visibility deteriorate slowly deteriorates moderate or poor

pressure falls at increasing rate stops falling falls if depression

deepening, otherwise

steady

dewpoint little change rises little change

Typical sequence of weather associated with a cold front

Front approching As it passes In cold air behind it

wind backs&increases close to front sudden veer probably backs a little

often with squall then steady; gusty&strong

cloud St&Sc thickening Ns Cb often total clearance, Cu

rain heavy rain near front heavy rain, peraphs hail&tunder usually fine

for 1-2hours,

then showers

visibility moderate to poor poor in rain very good

pressure falls near front sudden rise rise gradually levels off

dewpoint little change sudden fall little change

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Cold occlusion

38

Cold occlusion structure

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Warm occlusion

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Warm occlusion structure

41

Flow associated with developing Low

Le nubi

Understanding Clouds and fog Clouds are usually the most obvious feature of the sky. They both reflect weather patterns and play a role in what the weather does. The links below take you to a great deal of information about clouds. Locations of clouds - Low-level clouds: (generally found below 6,500 feet, or 2,000 meters) Low-level clouds are usually composed of liquid water droplets, but they can have snow and ice crystals in cold weather - Mid-level clouds: (generally found between 6,500 and 23,000 feet, or 2,000 and 7,000 meters) Most mid-level clouds are composed of liquid water droplets during summer and a liquid droplet-ice crystal mix during winter. Mid-level cloud names are preceded by an "alto" prefix. - High-level clouds (cirro clouds): (generally found above 20,000 feet, or 6,000 meters) High-level clouds are composed of ice crystals and tend to be very thin - Multi-level clouds: Cumulonimbus are the clouds that can produce lightning, thunder, heavy rains, hail, strong winds, and tornadoes. They are the tallest of all clouds that can span all cloud layers and extend above 60,000 feet.

1000 m=3281 ft

1 ft=0.305 m

1 m=3.28 ft

12 ÷ 18 km

Cumulus of Fair Weather: Widely separated heaps with flat bottoms and rounded tops. Small vertical development

Ground Fog: Layer of stratus lying on the ground. Forms at night and burns off by morning

Stratocumulus: A layer of clumps of cloud with thick and thin areas, often mixed with cumulus

Nimbostratus: Widespread thick layer of dark gray cloud producing steady rain

Lightning: Electrical discharge between cloud and ground, or cloud to cloud, that occurs in stormy weather cumulonimbus

Virga: Precipitation of ice or water that evaporates in warmer, drier lower regions

Crepuscular Rays: Open spaces between clouds allow sun to scatter light in 'dirty' air. This comes to eye as illusory diverging rays

Stratus: Poorly defined low cloud, usually with ragged edges

High (Alto) Stratocumulus: Higher layer of clumpy cloud, sometimes mixed with Cumulus

Cumulonimbus Shower: Widely separated showers or squalls of rain, and sometimes hail, developing in tall cloud

Cumulonimbus (Base and Top): A massive cloud system with flattish base and top sometimes flattened at base of the stratosphere. The source of lightning and thunder, hail, tornados, heavy localized rain showers

Sun Pillar: A beam, or pillar, of sunlight reflected upward from horizontal surfaces of hexagonal ice crystals

Cap Cloud: Lenticular cloud that sits on a mountain peak. Caused by ascending air on windward side and descending on the lee side

Billow Altocumulus: Unusual long rolls of cloud occurring in alto or cirrocumulus due to shearing motion. Clouds in regions of ascending air; spaces in regions of descending air

Swelling cumulus: Separated actively growing heap clouds with flattish bottoms and rounded, hard-edged tops

Altostratus: Layer of cloudy air, sometimes thick and preceding rain. Sun seen as if shining through ground glass

Altocumulus: Mid-level layered-heap cloud with many convective cells. Thin regions, descending air; thick regions, ascending air

Nimbostratus: Widespread thick layer of gray cloud producing steady snow

Cumulonimbus: Most active member of cumulus family; flattish base, tops sometimes extending 5 miles

Corona: Colored ring about moon and sun due to diffraction of light passing through a water crystal cloud

Mamma: Layer of cloud with pouch-like downward extensions, associated with cumulonimbus in latter stages of development

"Flying Saucer": Lenticular altocumulus with remarkable symmetry. Wind blows through stationary cloud

Cumulus Congestus: An active form of cumulus with many convective cells yielding cauliflower appearances to the top. Base is flattish representing the condensation level. Can produce showers

Cirro stratus: Widespread layer of thin veil-like ice crystal cloud. Though it appears thin it can be deceptively thick

Cirro cumulus: Layered cloud permeated with small cumuliform lumpiness

Cirrus: Ice crystal clouds in wide variety of feathery shapes, evaporating as they precipitate. (A type of virga)

Cumulonimbus (top): Top often resembles a flattened anvil which sometimes spreads ahead of main cloud mass. Ice crystal structure indicated by striations; stringiness

Halo, 22-1/2 degrees: Colored ring about sun or moon formed as light shines through cirrostratus ice crystals and experiences refraction. Interior, red; exterior, violet

Aurora Borealis (Northern Lights): Multi colored light comes from ionized atoms at top of the atmosphere in polar regions

Contrail: Cloud formed in wake of jet aircraft, indicative of upper level humidity and wind drift. Note vortex twisting motion

Pileus: Fibrous "lid" over cumulus congestus due to cooling uplift in upper air currents

Esempio: Previsione per il giorno 30/9/2017

Verificare con i dati meteorologici!!! https://www.windy.com/

https://www.windy.com/

ELEMENTI DI METEOROLOGIA PER COMITATI DI REGATA

Alessandro Pezzoli, PhD FRGS AFRIN PMP Professore Aggregato Weather Risk Management

Laurea Magistrale Economia dell’Ambiente, della Cultura e del Territorio – Università di Torino

Milano, 30 Settembre 2017

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