Thunderstorm categorized by cyclonic wind activity developed in Low Pressure region of Tropics.

Wind speed belonging to 63-112 km/h. Controls the Global Atmospheric Circulation Mechanism in Troposphere Ex. Hurricane,Typhon,Katrina,Rita, Includes tropical depressions, tropical storms Tropical Cyclone occur when Sea Surface Temperature (SST)>260C

TROPICS Located 23½° N to 23½° S. Large amount of solar radiation. Little seasonal variation. Warm water is the source of tremendous

latent heat source. High relative humidity promotes cumulus cloud development. Surface winds from the east

TROPICS

Sun generated tremendous heat increase the percentage of Moisture in air of Sea.

Higher wind speed and create a Low Pressure zone . More Condensation of moisture in air. Enthalpy of condensed moisture generate power in Warm core . Convective available Potential Energy is effected by large scale subsiding

air. Starting of Cyclonic wind rotation depending upon the rotation of earth.

# Anticlockwise rotation in Northern Hemisphere.

# Clockwise rotation in southern Hemisphere.

fig :1

Pressure gradiant force is represented by Blue Arrows.

Coriolis force is repreasented by Red Arrows.

Huge amount of greenhouse gas create a cover over the atmosphere. Sun generated heat can’t reflect to space. Hotter atmosphere, higher SST. Last 35 yr ,Global SST jump .50C

Fig2: Global Mean Surface temp. Anomalies Fig3: Sea Surface Temp Anomalies

Atmospheric water vapour pressure increases ,specially at tropical regain by increasing SST.

water vapour increase 1.3% per decades. Surface pressure falls Enhancing tropical convection More power generate by huge enthalpy of condensed moisture. Tropical storm intensity and frequency increase.

Fig4: The Low Pressure zone occurs at higher SST

Due to SST increase, wind speed also change in upward dip in fig 5 and cyclone intensity increase.

Fig5:Atlantic Tropical

Cyclone intensity vs SST

Fig 6: Global Hurricane intensity change Fig 7:Regional hurricane intensity change

YEAR AVG. STORM

AVG. HURRICANE

AVG.DEVASTATIVE HURRICANE

1970-2004 8.6 5 1.5

1995-2004 13.6 7.8 8.6