AY Honors/Weather - Advanced/Answer Key

CHRISTINA WAS HEREE!!!!!!!

Effects on weather

Vertical velocity at 500 hPa, July average. Ascent (negative values) is a tracer for the ITCZ and is concentrated close to the solar equator; descent (positive values) is more diffuse.

Variation in the location of the intertropical convergence zone drastically affects rainfall in many equatorial nations, resulting in the wet and dry seasons of the tropics rather than the cold and warm seasons of higher latitudes. Longer term changes in the intertropical convergence zone can result in severe droughts or flooding in nearby areas.

Within the ITCZ the average winds are slight, unlike the zones north and south of the equator where the trade winds feed in. Early sailors named this belt of calm the doldrums because of the inactivity and stagnation they found themselves in after days of no wind.[1] To find oneself becalmed in this region in a hot and muggy climate could mean death in an era when wind was the only major motive force.

Role in tropical cyclone formation

Tropical cyclogenesis depends upon low-level vorticity as one of its six requirements, and the ITCZ/monsoon trough fills this role as it is a zone of wind change and speed, otherwise known as horizontal wind shear. As the ITCZ migrates more than 500 km from the equator during the respective hemisphere's summer season, increasing coriolis force allows the formation of tropical cyclones within this zone more possible. In the north Atlantic and the northeastern Pacific oceans, tropical waves move along the axis of the ITCZ causing an increase in thunderstorm activity, and under weak vertical wind shear, these clusters of thunderstorms can become tropical cyclones.

See also

• Horse latitudes
• Monsoon trough
• Tropical cyclogenesis

References

• Short NASA article with high resolution photo

Christina was here