What is the equatorial zone known as
the tropical rain climate
what are the Arid zones known as
the Dry Climate
what are Warm Temperature zones known as
Mid Latitude Climate
What is the snow zone known as
the sub-artic climate
what is the polar zone known as
the snow climate
location of tropical rain climate
10 degrees either side of the equator
temperature in tropical rain climate
highs up to 35 degrees, lows down to 20 degrees
humidity in tropical rain climate
high humidity and convective weather
is there a dry season in tropical rain climate
no
winds in tropical rain climate
light winds
classification of tropical rain climate
monsoonal
tropical savannah climate boundary
10-25 degrees of latitude
temperature in savannah climate
high with mean temperature above 18 snd diurnal and seasonal variation increasing with latitude
rain in savannah climate
wet in summer and dry in winter with the wet season associated with the overhead sun
winds in savannah climate
dry trade winds in winter
Dry climate subdivisions
Desert and Steppe
How do steppe and desert regions differ
steppe regions are wetter and have more vegetation
Pressure in dry climate
high
temperature in dry climate
very hot with large daily and seasonal variations
precipitation in dry climate
on equatorial side in summer and on polar side in winter
winds in dry climate
prevalent trade wind
winds in cool mid latitude climate
predominant westerly winds and passage of frontal depressions
is there a dry season in a cool mid latitude climate
no
are there seasonal variations in a cool mid latitude climate
yes
mid latitude climate in warm temperate zone
transition climate
transitional climate
significant variations due to the seasonal position of the sun
winter conditions in warm mid latitude climate
similar to cool temperate zone
summer conditions in warm mid latitude climate
associate with arid zone
conditions in sub-artic climate
cold dry winter and hot summer
seasonal variation is Snow Climate
Extreme seasonal variation
winter in snow climate
extremely cold
why is the ITCZ further away from the equator over land masses
land warms quicker
Mesoscale Convective System
complex thunderstorms on larger scale than individual ones that can last for several hours or more
where are MCS found
ITCZ
Why is ITCZ referred to as doldroms
lack of horizontal air movement due to convective activity
Monsoon
seasonal changes in circulation and precipitation caused by the asymmetric heating of land and sea masses
monsoon in India is summer
south west winds brings in warm moist air from sea and heavy precipitation
monsoon in India in winter
North east Monsoon with drier air
Where is affected by Monsoon winds
India, coastal areas of Africa, regions of North America and Chile
ITCZ in summer
very moist air from Atlantic combined with thermal and convergent uplift produces significant precipitation in northern Africa
Harmattan
hot dry wind that picks up sand from Sahara along its fetch which can cause significant reductions in visibility
harmattan in winter
can be quite cool
Weather over East Asia in winter
north easterly flow driven by Siberian high
weather is East Asia in summer
significant precipitation associated with the Monsoon in July and August due to warm moist Pacific Air drawn over continent
What is Australian summer monsoon driven by
strong heat lowers over Northern Australia
Monsoonal flow in Northern Australia
not as strong or steady as the Indian Monsoon
Onset of monsoonal flow in Northern Australia
occurs during January
what happens as southeast Asian winter monsoon strengthens
flow penetrates deeper into tropical latitudes crossing equator and turning westerly until April with the return of easterly trade winds
Easterly waves
troughs of low pressure that flow from east to west
what can easterly waves cause
disturbed weather along ICTZ and hurricanes
easterly waves cased by
african easterly jet which is large scale sea breeze
African easterly jet
removes air over the Atlantic off the West Africa Coast and low pressure area formed is a trough producing convective weather and thunderstorm activity
what is mid latitude weather influenced by
position of polar front
how do depressions produced by the polar front travel
west to east
where are westerly winds in mid latitudes produces
high pressure regions in the sub tropical belt
westerly winds in the southern hemisphere
very fast as little land mass to impede process so they are referred to as the roaring forties
Location of the Mistral
flows south down the Rhone Valley and out into the Gulf of Lyons
what is associated with the Mistral
genoa low in the gold of Gulf of Genoa
when does the Mistral occur
airflow through the Rhone Valley is enhanced when an area of high pressure lies to the west and a polar front depression to the east
what airstream feeds the Mistral
polar maritime
what makes the Mistral faster
katabatibc winds and fuelling effects
Mistral speed
in excess of 75kts
Where does the Bora occur
blown down Dynamic coastal mountain range
when does Bora occur
when there is high pressure over central europe and the balkans and low pressure over the med
what causes Bora to be so strong
Katabatic effect
what speeds can Bora reach
70kts with gusts in excess of 100kts
What is the Scirroco
hot, dry dusty wind that blows from North Africa across the med
Other names for the Scirroco
Chilli, Ghibli and Khamsin
What causes Scirroco
blows easterly due to depressions transiting the Mediterranean
max speed of Scirroco
around 55kts
weather caused by Scirroco
moisture picked up from med can cause low cloud and drizzle
When does Fohn wind occur
when air in horizontal motion meets a significant mountain range and it is forced over the top
weather caused by Fohn wind
cloud due to the air adiabatically cooling at the DALR and then the SALR and warms as it descends
why does Fohn wind warm Lee side of mountain
air cools less at SALR and more at DALR
Where does the name Fohn wind come from
local wind in the alps
Chinnok
name for Fohn wind in Rockies
where can outbreaks of polar air reach
sub tropical latitudes – below 30N
what can outbreaks of polar air cause
unseasonably cold weather and snowfall between 30-50N
Blizzard
polar air outbreaks in northern hemisphere
Pampero
polar air outbreaks in southern hemisphere
what causes polar air outbreaks
cooler air descending and cooling at polar caps reaches critical mass and breaks away
cold air pool
deep cold core aloft which is undetectable at ground level
what causes cold air pools
left over from polar air outbreak
cold air pool conditions
unstable due cold air on top of warm moist air
what causes cold air pool conditions to dissapate
dissipation of cold air pool itself
lifespan of cold air pool
several days
diameter of cold air pool
300nm-600nm
vertical extent of cold air pool
10000ft to 30000ft
where do cold air pools appear over Europe
behind cold front7
Untrue about the Tropopause
Temp starts to fall serverly above tropopause
The tropopause breaks are important for aviation because
The cores of jet streams can be located near these breaks
At North Atlantic Lat of 50 deg in winter the height of the tropopause is approximately
31000 ft ie average height 16km x cos(lat)
Majority of ozone found
In stratosphere relatively high round 30km
Lowest layer of the atmosphere
Troposphere
The inversion in the lower troposphere created by old H psi system during day or night
Subsidence inversion
The 2 most important methods of heat transfer from surface to higher levels of the troposphere
Formation of convection clouds and long wave radiation
During a valley inversion
Over night cool dense air as a result of radiation cooling will descend along mountain slopes into the basin and lest to the development of a valley inversion
A significant inversion at low height is a characteristic of
Nocturnal radiation
On a clear sky in summer, continental ground surface, wind calm the minimum temperature is reached approximately
Half an hour after sunrise (30 min after sunrise)
The primary cause of all changes in the Earth’s weather is
Is variation of solar energy received by the earth surface
1.98 deg c per
1000 ft
0.65 deg c per
100m
Frequency band of Wx radar
8-12GHz
wavelength of wx radar
2.5-4cm
Ts avoidance
20nm above FL200 and 10nm below FL200
Hadley cells
series of rising and descending cell circulations
air in equatorial regions
rises due to surface heat and diverges at higher levels and then sinks cause sub-tropical high pressure belts
Surface air rotation around the sub tropical highs
cause trade winds through Coriolis force
Air rising on the polar front
caused by air from sub-tropical highs meeting polar air and forms polar front depressions
wladimir koppen
classified climates based on vegetation
equatorial zone
also known as the tropical rain climate between 10S and 10N
equatorial zone sub zones
tropical rain forest and tropical savannah
conditions in tropical rain forest
high temperature up to 35 degrees with little seasonal variation, no dry season, light winds, high humidity and high amount of convective weather
location of tropical savannah
10 to 25N and S
conditions in tropical savannah
high mean temperature of 18 degrees, increasing diurnal and seasonal variation with latitude, wet in summer and dry in winter with dry trade winds in winter
Arid zone
AKA dry climate with 2 zones
zones of arid zone
steppe climate and desert climate
conditions in arid zone
high pressure, hot in summer with large diurnal and seasonal variations, precipitation in summer on equatorial side and polar side in winter, prevalent trade wind
temperate zone
AKA mid latitude climate split into the warm and cold temperate zones
characteristics of warm temperate zone
westerly wind aiding the passage of frontal depressions, no dry season and seasonal variations, a transitional climate
what causes warm summer in transitional climate
sub tropical highs which are associated with the arid zone
snow zone
aka sub-artic climate covering areas of continental North America, Scandinavia, and former USSR
conditions in snow zone
cold dry in winter and hot in summer with average temperature of 0
polar zone
aka snow climate, extreme season variation, extreme cold winters and period of constant dark and light
ICTZ further from equator over land masses
land masses are warmed more quickly than sea
northeast trade winds
converge in a low pressure zone creating ITCZ
solar heating in ITCZ
forces air to rise through convection and leads to unstable conditions combined with high lapse rates
mesoscale convective system
triggered by ITCZ, complex of thunderstorms and larger scale, lasting longer
wettest zone on earth
equatorial zone with 200 days of precip per year
monsoon
seasonal changes caused by asymmetric heating of the land masses
cause of windshift with monsoon
differential in surface heating between the land and the sea
southwest monsson
affects in summer with warm moist air and precip
Pressure system with SW monsoon affecting Inda
low over Pakistan
north east monsoon
affect in winter with a much drier air mass
pressure systems with north east monsoon affecting India
high over Tibet
places experiencing monsoon other than Inda
Northern Australia, coastal Africa, North America and Chile
monsoon of western sub-saharan Africa
due to temperature and humidity difference between Sahara and Atlantic and shift of ITCZ
August in western sub-saharan Africa
ITCZ north over Sahara, moist air from Atlantic blows in causing thermal and convergent uplight causing significant precip
January in sub-saharan Africa
ITCZ further south, very hot and dry and NE trade winds cause Harmattan
Harmattan
Very hot dry wind blowing between November and April that can cause dust and sandstorms up to FL150
East Asia Monsoon
Cold north easterly flow in winter driven by the Siberian Highs and a warm moist south westerly flow in summer driven by Asian low causing significant precip
ITCZ in winter
moves south and lies over Indonesia and northern Australia
Siberian high
lies over Asia in winter
Australia Summer monsoon
driven by strong heat lows like Asian monsoon, not as strong or steady as Indian monsoon, and penetrates into the tropical latitudes as it strengthens
when does the Australian summer monsoon happen
January
trade winds in Jan
cross equator near Indonesia and turn westerly flowing across northern Australia
how long does Australian summer monsoon last
until the easterlies return
easterly waves
disturbed weather along ITCZ that travel east to west
what are easterly waves
troughs of low pressure south of the azores high generated by the african easterly jet
african easterly jet
removes air over atlantic forming low pressure area which forms trough causing convective weather, blows generally in summer
mid latitude weather
influenced by the position of the polar front and makes westerly depressions
pressure systems in winter
migrate southwards like the ITCZ
Mistral
flows south down the Rhône valley into the Gulf of Lyons, mainly in winter months due to the prevalent pressure systems
pressure systems associated with Mistral
Genoa low
what enhances the Mistral
high pressure to the west and polar front depression to the east
what often feeds the mistral
maritime air masses
what fuels the mistral
katabatic winds
mistral strength
up to 75kt can last several days
Bora
blows down the Dinaric mountain range in winter
pressure systems for the Bora
high pressure over central europe and low pressure over the med
strength of Bora
cold and gusty averaging 70kts helped on with katabatic winds
Scirocco
Hot, dry and dusty winds from north africa across the Med
scirocco also known as
Chilli, ghiblii, Khamsin
when is the scirocco easterly
when produced by depressions crossing the med
max speed of scirocco
55kt
weather with scirocco
low cloud and drizzle with the moisture picked up from the med
Föhn wind
air meeting mountain range forced up and cooled adiabatically forming cloud if cooled below dew point
warming with Föhn wind
up to 10 degrees on Leeward side
Polar air outbreaks
can reach subtropical regions down to 30N/S bringing unseasonably cold weather
snow fall from polar air outbreaks
between 30N-50N as cold air mixes with warm air
other names for polar air outbreaks
blizzard in northern hemisphere and pamper in southern hemisphere
formation of polar air outbreak
cooling, descending air reaches critical mass and breaks away from the polar air mass
cold air pool
deep, cold core aloft undetectable at ground level
what is a cold air pool made of
remaining cold air from polar air outbreak
cold air pool over warm moist air
unstable conditions can produce area of convective cloud
when does a cold air pool dissipate
after mixing
life span of cold air pool
up to several days
dimensions of cold air pool
300nm-600nm in diameter from FL100 to FL300
where to cold air pools tend to form
half of them behind cold front and are difficult to predict
Land and sea breezes
produced by pressure differential cased by temperature difference – pressure differential can cause change by 500ft to 1000ft
Sea breezes
tend to form in afternoon and produce fall in temperature and increase in humidity
effects of sea breeze
felt up to 1000ft, 10-15nm either side of the coast line and can cause small cumuliform clouds
strength of sea breeze
up to 10kt and deflected to the right in the northern hemisphere
anabatic winds
slope heated and air is warmed through conduction causing air to be less dense and rise and is not usually noticeable due to irregular topography
what can energise anabatic winds
funnel feature of valley
katabatic winds
slope cools, cooling the air through conduction, air is denser and sinks and can cause formation of fog and mist
when are katabatic winds commonly found
at night
example of katabatic winds
Bora to an extent and can blow during daylight hours due to the cooling effect of the land in winter
what enhances the bora
funnel affect of topography and prevailing pressure systems
ravine or valley wind
generally follows the contours if the atmosphere is stable
when is a ravine or valley wind subject to the venturi effect
when the valley is aligned in the general direction of the wind
example of ravine or valley wind
Mistral
headland effect
wind blowing parallel to coast and headland squeezes isobars increasing the pressure gradient and windspeed
when does the föhn wind cause more heating
when more water is deposited
conditions for mountain waves
wind 30 degrees either side of normal to mountains increasing with height with little variation on the same heading, and stable layer of atmosphere with less stable atmosphere above
windspeed for mountain waves
15kt at crest
wavelength of mountain wave =
knots/7
mountain wave in stratosphere
caused by irregular features near initiation mountains and are of greater length than those in the troposphere
double amplitude of mountain waves
1500ft up to 1000fpm Vertical Speeds
Lenticular clouds
form in the stable layer of the standing wave
rotor clouds
Ragged Cu or Sc, parallel to downwind ridge rotating about the horizontal axis
number of rotors
1 or 2
Cap clouds
usually form on the ridge crest an can be extended by strong winds to create a föhn wall but can be obscured by frontal clouds