Intro. to Meteorological Analysis– MT 2230 Plymouth State University LAB 7 NOTES Dr. Sam Miller Intro. to Meteorological Analysis– MT 2230 Plymouth State University 1

Troughs and Ridges

Troughs & Ridges Ridge – elongated region of clockwise curvature in the wind field Anticyclonic Drawn as a zigzagging line Trough – elongated region of counterclockwise curvature in the wind field Cyclonic Drawn as a curved line (sometimes dashed)

Troughs & Ridges Both are visible in the wind field and the height contours

WIND FLOW ALOFT

REGIONS OF CYCLONIC CURVATURE (AXES MARK SHARPEST TURNING)

REGION OF ANTICYCLONIC CURVATURE (AXIS MARKS SHARPEST TURNING)

TROUGH (TROF) RIDGE TROUGH (TROF)

Divergence & Convergence Aloft

TROUGH (TROF) RIDGE TROUGH (TROF)

HEIGHT CONTOURS

L LOW HEIGHTS H H HIGH HEIGHTS HIGH HEIGHTS

Recall characteristics of forces in the free troposphere: Pressure Gradient Force (PGF): Points across isobars (or height contours) toward lower pressure (heights) Coriolis Force (CoF): Points 90 degrees to the right of the wind direction (Northern Hemisphere) Centrifugal Force (CeF): Points away from the focus of curvature (not present in straight flow)

L H H

REGIONS OF STRAIGHT-LINE FLOW

REGIONS OF CURVED FLOW L H H

FORCES IN CURVED REGIONS CeF CeF PGF PGF L CoF CoF FORCES IN CURVED REGIONS H H PGF CoF CeF

CeF CeF PGF PGF L CoF CoF H H PGF CoF CeF

CeF CeF PGF PGF L CoF CoF H H PGF CoF PGF & CeF IN OPPOSITION CeF

L H H CeF CeF PGF PGF CoF CoF WIND SLOWS DOWN PGF IN BASE OF TROUGH

CeF PGF & CeF ARE ADDITIVE CeF PGF PGF L CoF CoF H H PGF CoF CeF

WIND SPEEDS UP AT TOP OF RIDGE CeF CeF WIND SPEEDS UP AT TOP OF RIDGE PGF PGF L CoF CoF H H PGF CoF CeF

MAXIMUM SPEED MAXIMUM SPEED L H H MINIMUM SPEED

L SLOWING DOWN SPEEDING UP H H

L CONVERGENCE ALOFT DIVERGENCE ALOFT H H

Implications of Divergence Aloft

Divergence occurs downwind of an upper-level trough and upwind of an upper-level ridge ALOFT H

UP DIVERGENCE ALOFT SOUTHWEST NORTHEAST POLAR JET SOUTHWEST NORTHEAST

UP MASS REMOVAL SOUTHWEST NORTHEAST POLAR JET MASS REMOVAL SOUTHWEST NORTHEAST

UP MASS REMOVAL SOUTHWEST NORTHEAST TROPOPAUSE PREVENTS VERTICAL MOTION UP POLAR JET MASS REMOVAL SOUTHWEST NORTHEAST

MASS PULLED UP FROM BELOW TO REPLACE MASS REMOVED BY DIVERGENCE ALOFT TROPOPAUSE PREVENTS VERTICAL MOTION UP POLAR JET MASS PULLED UP FROM BELOW TO REPLACE MASS REMOVED BY DIVERGENCE ALOFT SOUTHWEST NORTHEAST

UPWARD VERTICAL MOTION IS INDUCED TROPOPAUSE PREVENTS VERTICAL MOTION UP POLAR JET UPWARD VERTICAL MOTION IS INDUCED SOUTHWEST NORTHEAST

UP MASS REMOVAL SOUTHWEST NORTHEAST TROPOPAUSE PREVENTS VERTICAL MOTION UP POLAR JET MASS REMOVAL SOUTHWEST NORTHEAST

LESS MASS = PRESSURE FALLS TROPOPAUSE PREVENTS VERTICAL MOTION UP POLAR JET LESS MASS = PRESSURE FALLS SOUTHWEST NORTHEAST

AREA OF LOW PRESSURE ON SURFACE TROPOPAUSE PREVENTS VERTICAL MOTION UP POLAR JET L AREA OF LOW PRESSURE ON SURFACE SOUTHWEST NORTHEAST

HIGHER PRESSURE ON ALL SIDES TROPOPAUSE PREVENTS VERTICAL MOTION UP POLAR JET H L H HIGHER PRESSURE ON ALL SIDES SOUTHWEST NORTHEAST

H L H UP SOUTHWEST NORTHEAST TROPOPAUSE PREVENTS VERTICAL MOTION POLAR JET TOP OF ATMOSPHERIC BOUNDARY LAYER H L H SOUTHWEST NORTHEAST

H L H UP SOUTHWEST NORTHEAST TROPOPAUSE PREVENTS VERTICAL MOTION POLAR JET TOP OF ATMOSPHERIC BOUNDARY LAYER H L H FRICTION PRESENT: WIND CROSSES TO LOWER PRESSURE SOUTHWEST NORTHEAST

H L H UP SOUTHWEST NORTHEAST TROPOPAUSE PREVENTS VERTICAL MOTION POLAR JET TOP OF ATMOSPHERIC BOUNDARY LAYER H L H LOW-LEVEL CONVERGENCE SOUTHWEST NORTHEAST

UPWARD VERTICAL MOTION DIVERGENCE ALOFT POLAR JET UPWARD VERTICAL MOTION (CHIMNEY) L LOW-LEVEL CONVERGENCE SOUTHWEST NORTHEAST

Chimney SURFACE

Implications of Convergence Aloft

Convergence occurs downwind of an upper-level ridge and upwind of an upper-level trough ALOFT

UP CONVERGENCE ALOFT NORTHWEST SOUTHEAST POLAR JET NORTHWEST SOUTHEAST

UP MASS PILES UP NORTHWEST SOUTHEAST TROPOPAUSE PREVENTS VERTICAL MOTION UP POLAR JET MASS PILES UP NORTHWEST SOUTHEAST

UP EXCESS MASS SINKS NORTHWEST SOUTHEAST TROPOPAUSE PREVENTS VERTICAL MOTION UP POLAR JET EXCESS MASS SINKS NORTHWEST SOUTHEAST

DOWNWARD VERTICAL MOTION IS INDUCED TROPOPAUSE PREVENTS VERTICAL MOTION UP POLAR JET DOWNWARD VERTICAL MOTION IS INDUCED NORTHWEST SOUTHEAST

UP MASS ADDED NORTHWEST SOUTHEAST TROPOPAUSE PREVENTS VERTICAL MOTION UP POLAR JET MASS ADDED NORTHWEST SOUTHEAST

ADDITIONAL MASS = PRESSURE RISES TROPOPAUSE PREVENTS VERTICAL MOTION UP POLAR JET ADDITIONAL MASS = PRESSURE RISES NORTHWEST SOUTHEAST

AREA OF HIGH PRESSURE ON SURFACE TROPOPAUSE PREVENTS VERTICAL MOTION UP POLAR JET H AREA OF HIGH PRESSURE ON SURFACE NORTHWEST SOUTHEAST

LOWER PRESSURE ON ALL SIDES TROPOPAUSE PREVENTS VERTICAL MOTION UP POLAR JET L H L LOWER PRESSURE ON ALL SIDES NORTHWEST SOUTHEAST

L H L UP NORTHWEST SOUTHEAST TROPOPAUSE PREVENTS VERTICAL MOTION POLAR JET TOP OF ATMOSPHERIC BOUNDARY LAYER L H L FRICTION PRESENT: WIND CROSSES TO LOWER PRESSURE NORTHWEST SOUTHEAST

L H L UP NORTHWEST SOUTHEAST TROPOPAUSE PREVENTS VERTICAL MOTION POLAR JET TOP OF ATMOSPHERIC BOUNDARY LAYER L H L LOW-LEVEL DIVERGENCE NORTHWEST SOUTHEAST

DOWNWARD VERTICAL MOTION UP CONVERGENCE ALOFT POLAR JET DOWNWARD VERTICAL MOTION (DAMPER) H LOW-LEVEL DIVERGENCE NORTHWEST SOUTHEAST

Damper SURFACE

Review

TROPOPAUSE CHIMNEY DAMPER SURFACE