FRONTS Chapter 11 Ben Franklins Storm Nov 2

FRONTS (Chapter 11)

Ben Franklin’s Storm (Nov. 2, 1743) 500 mb Boston Philadelphia L L

Norwegian Cyclone Model (pp. 322– 324)

Typical Cold Front • Convective precipitation • 50– 100 mile wide band along front

Cold Front Cross-Section

Typical Warm Front • Clouds and precipitation precede surface front • Stratiform clouds starting about 750 miles from front • Stratiform precipitation starting about 350 miles from front “Overrunning”

Warm Front Cross-Section

Warm Front Cross-Section WARM AIR COLD AIR

OCCLUDED FRONTS • Heavy precipitation along front • Convective or stratiform • Short duration

Occluded Front Cross-Section (“Cold Occlusion”)

“Warm Occlusion”

Occluded Front Cross-Section (“Warm Occlusion”)

“Warm Occlusion”

Cold Occlusion Warm Occlusion

(QUASI-) STATIONARY FRONT Partly cloudy or cloudy with widespread stratiform precipitation

Cyclone Family Cold Air Warm Air (pp. 306– 319)

Station Temp SLP trend CC Wind dir Dew point Precip A Low Falling Cirrostratus SE Moderate No B Low Falling Overcast, (nb)stratus SE Moderate No, chance light drizzle C Low Falling Overcast, nb SE -stratus Slightly higher Continuous rain D Lower Falling then nb-stratus rising or c-nimbus NW to W Slightly lower (? ) Mod-hvy rain showers E Lower Rising Clearing NW Lower No F Lower Rising No clouds NW Lower, stabilizing No

c. P or m. P (Atlantic) c. P m. T

Clouds

Precipitation