Summer Monsoon regimes of the World

Monsoon winds from Southern Hemisphere

Global Pressure Pattern in July

Onset of Monsoon dates over India

Wind shears in Monsoon Monsoon means strong reversal of winds implying wind shear conditions, creating a hazardous flight environ Winds at lower levels at 3000 to 5000 ft peninsular India experiences low level Jet streams

Low Level Jet Stream in SW monsoon

6000ft Westerly Winds 20 knots Aircraft suffers a ballooning effect on account of low-level jet stream Shear Zone 6000ft Low level westerly jet stream of 40 knots and more Temporary increase in airspeed giving a greater lift and significantly reduce the rate of decent and returning below the intended decent

Opposite situations will occur in winter with inversion of temperature over the helipad in association with foggy conditions Shear Zone Calm or light winds

Vertical/Slant visibility is deceptive

LATE CHIEF MINISTER, MR. Y LATE CHIEF MINISTER, MR.Y.RAJASEKAR REDDY’S HELICOPTER CRASH http://www.youtube.com/watch?v=q3QeaKrdcXI&feature=fvwrel

Flight Regulation for Helicopters The helicopters are strictly expected to fly only under VMC. Due to circumstances beyond the control, sometimes the craft has to enter the cloud. Hence some elementary knowledge of conditions for the formation of clouds and their identification, to be refreshed by the participants is desirable

The Formation of Clouds Cloud formation is associated with rising air Rising air cools adiabatically The air reaches its dew point Cloud is formed The form (shape) of the cloud depends upon the stability of the rising air Layer (stratiform) cloud forms in stable air Heaped (cumuliform) cloud forms in unstable air

Clouds can be categorized on the basis of the “lifting mechanism” that is the process which causes the air to move upwards

The formation of clouds There are 4 categories: Convection cloud Orographic cloud Turbulence cloud Frontal cloud

Convection cloud Air is heated at the surface Air rises, cools adiabatically and reaches its dewpoint Cumulus or cumulonimbus cloud forms

Formation of convection cloud

Convection cloud Convection cloud can occur over land and sea It often forms when cold air from high latitudes is moving southwards over the ocean The rising air currents are called thermals

Formation of Convection cloud

Orographic cloud Air meets high ground Air rises, cools adiabatically and reaches its dewpoint Cloud can be stratiform (stable air) or cumuliform (unstable air)

Formation of Orographic cloud

Orographic cloud The extent of the cloud depends upon the extent of the high ground The height of the cloud is controlled by the height at which it reaches its dewpoint Famous orographic clouds include the tablecloth and the levanter

Turbulence cloud The air is travelling across a colder surface The air moves upwards as part of the turbulence The air cools by conduction at the surface and adiabatically as it rises The cloud formed is stratus cloud

Formation of Turbulence cloud

Stratus cloud

Cirrus cloud

Nimbostratus

Frontal cloud The warmer air rises upwards because it is less dense The rising air cools adiabatically and reaches its dewpoint The cloud will be Stform in stable air and Cuform in unstable air

Formation of frontal cloud: warm front

Formation of frontal cloud: cold front

Cloud Names

WMO System

Cloud Names Cirrus - Means a lock of hair or a tuft of horsehair Cumulus - Means an accumulation or a pile Stratus- Means to spread out, to cover a layer Nimbus – Means Rain

Cloud Classifications Height W.M.O. Form Formation

Classification by Height Cloud Base 3 – 18 km Classification by Height High Cloud Base 3 – 18 km Medium Cloud Base 2 – 8 km Low Cloud Base 0 – 2 km Cloud Base 0 – 2 km Great Vertical Extent

Stratocumulus

Genera High Clouds Cirrus Cirrocumulus Cirrostratus

Cirrus Detached clouds in the form of white, delicate filaments or white or mostly white patches or narrow bands. These clouds have a fibrous (hair-like) appearance, or a silky sheen, or both.

Cirrocumulus Thin, white patch, sheet of layer of cloud without shading, composed of very small elements in the form of grains, ripples, etc. merged or separate, and more or less regularly arranged, most of the elements have an apparent width of less than one degree.

Cirrostratus Transparent, whitish cloud veil of fibrous (hair-like) or smooth appearance, totally or partly covering the sky, and generally producing halo phenomena.

Genera Medium Clouds Altocumulus Altostratus Nimbostratus

Altocumulus White or grey, or both white and grey, patch, sheet or layer of cloud, generally with shading, composed of laminae, rounded masses, rolls etc. which are sometimes partly fibrous or diffuse and which may or may not be merged; most of the regularly arranged small elements usually have an apparent width between one and five degrees.

Altostratus Greyish or bluish cloud sheet or layer of striated, fibrous or uniform appearance, totally or partly covering the sky, and having parts thin enough to reveal the sun at least vaguely, as through ground glass. Altostratus does not show halo phenomena.

Nimbostratus Grey cloud layer, often dark, the appearance of which is rendered diffuse by more or less continuously falling rain or snow, which in most cases reaches the ground. It is thick enough throughout to blot out the sun. Low, ragged clouds frequently occur below the layer, with which they may or may not merge

Genera Low Clouds Stratocumulus Stratus

Stratus Generally grey cloud layer with a fairly uniform base, which may give drizzle, ice prisms or snow grains. When the sun is visible through the cloud, its outline is clearly discernible. Stratus does not produce halo phenomena except, possibly, at very low temperatures. Sometimes stratus appears in the form of ragged patches.

Genera Clouds of Great Vertical Extent Cumulus Cumulonimbus

Cumulus Detached clouds, generally dense and with sharp outlines, developing vertically in the form of rising mounds, domes or towers, of which the bulging upper part often resembles a cauliflower the sunlit parts of these clouds are mostly brilliant white, their base is relatively dark and nearly horizontal. Sometimes cumulus is ragged.

Cumulonimbus Heavy and dense cloud, with a considerable vertical extent, in the form of a mountain or huge towers. At least part of its upper portion is usually smooth, of fibrous or striated, and nearly always flattened; this part often spreads out in the shape of an anvil or vast plume. Under the base of this cloud which is often very dark, there are frequently low ragged clouds either merged with it or not, and precipitation sometimes in the form of virga .  

Classification by Form Cirriform Cumuliform Stratiform

Cirriform High Cloud Tenuous Ice crystals Associated with depressions

Cumuliform Unstable Air Discrete clouds Vigorous upward motion Showers

Stratiform Stable Air Widespread Slow upward motion Continuous precipitation

The Importance of Dew point Temperature During pre flight planning, if you find temperature and dew point temperature are very close, you are bound to encounter clouds The cloud base will be around (T– Td ) x 400 ft The Difference between ceiling and base of cloud The term ceiling is applicable when 5/8 or more is below 20,000 feet, otherwise the term base.

Reverting back to Monsoon Flying the following slides can amplify the hazards of aviation

Runway highly contaminated due to heavy rain Sumai Island 25 KTS SW WINDS Runway highly contaminated due to heavy rain 56

A passenger plane skidded off the runway and crashed into a building after landing on the Thai resort island of Samui on Tuesday, killing the chief pilot and injuring at least seven people including foreign tourists. The Bangkok Airways flight landed in stormy weather and hit the airport's old air traffic control tower, which had been converted into a fire station, said Kanikka Kemawutanond, director-general of the Department of Civil Aviation. The co-pilot and six tourists were hurt. 57

The Controls of Monsoon ITCZ Elnino Indian Ocean Dipolar Temperature effect The Effect of Mascrean high pressure area Madden Julian Oscillation 58

General Circulation

Animated circulation of global winds 61

AIRFRANCE-447 CRASH ON 1ST JUNE 2009

ITCZ EQ PARIS ETA 9UTC 1ST JUNE ATLANTIC AFRICA CRASH 2UTC 1ST JUNE LAT 4N LONG30W ITCZ EQ CRASH 2UTC 1ST JUNE BRAZIL RIO DEP 22UTC 31ST MAY

CRASH

Extreme Turbulence 72

Radar is only an aid not an end by itself Contributing safety factors - The crew did not detect an area of convective turbulence (cloud), either visually or by radar. - The aircraft penetrated an area of severe convective turbulence. - The area of convective turbulence encountered by the aircraft comprised ice crystals. - The aircraft radar had limited capability to detect cloud that comprised ice crystals. [Minor safety issue]