Stratus CloudBase and CloudTop

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Stratus Cloud-Base and Cloud-Top Height
Measurements
LT D. Adam Newton OC3570
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Outline

• What am I trying to do?
• What did I do?
• What does the data look like?
• What are the results?
• Why are the results the way they are?

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What am I trying to do?

• Correlate the observed cloud-base heights and the
  rawinsonde data.
• Determine the cloud-top heights from the
  rawinsonde data.
• Compare the cloud-top heights of the upward and
  downward moving sondes.
• Determine reasons for the observations.

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What did I do?

• Created plots of the appropriate sondes from the
  surface to 1300m.
• Found the Relative Humidity of the Observed
  Cloud-Base height.
• Compared the above to the Max Relative Humidity.
• Determined the Cloud-Top Height threshold.
• Compared the up and down leg Cloud-Top Heights.
• Attempted to explain the results.

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8/8 Stratus
CTHt Up 680 CTHt Down 590
Obs CBHt 558m
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Strato-Cu
CTHt Up 980 Down No Cloud
Obs CBHt 640m
120 min gt17000m
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Partly Sunny, Broken Strato-Cu
CTHt Up 800 CTHt Down 580
Obs CBHt 683m
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Drizzle, 8/8 Strato-Cu
CTHt Up 770 CTHt Down 630
Night-time (Dark)
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Drizzle, 7/8 Strato-Cu
CTHt Up 760 Down No Cloud
Obs CBHt 421m
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8/8 Strato-Cu
CTHt Up 510 CTHt Down 390
Obs CBHt 236m
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8/8
CTHt Up 470 Down No Cloud
Obs CBHt 215m
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8/8 Thin Stratus, sun visible earlier,
some cloud, ahost at surface.
CTHt Up 380 Down No Cloud
Obs CBHt 203m
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8/8 Strato-Cu
CTHt Up 610 CTHt Down 490
145 min gt18000m
Obs CBHt 311m
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Max Ht 1067m Possible Balloon Pop
8/8 Strato-Cu,
CTHt Up 570 CTHt Down 530
Obs CBHt 459m
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8/8 Strato-Cu
CTHt Up 620 CTHt Down 600
Obs CBHt 175m
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6/8 Stratus, 1/8 low-level broken Cu,
sun above, clearer around
CTHt Up 650 Down No Cloud
Obs CBHt 617m
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Misty
CTHt Up 730 CTHt Down 710
Night-time (Dark)
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8/8 Strato-Cu
CTHt Up 950 Down No Data
65 min gt15000m
Obs CBHt 506m
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Why?
Cloud-Base Height Observed Cloud-Base Heights
are not consistent. The Relative Humidity data
is incorrect. -sensor lag -sensor error Clouds
can form at a Relative Humidity of lt100.
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Why?
Cloud-Top Height Up-leg CTHt is too high and
Down-leg CTHt is too low due to sensor lag or
wetting. Sondes dont come down where they went
up. -mean transport offshore where the inversion
height is lower.
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?