slide1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
UPPER-LEVEL WINDS PowerPoint Presentation
Download Presentation
UPPER-LEVEL WINDS

Loading in 2 Seconds...

play fullscreen
1 / 26

UPPER-LEVEL WINDS - PowerPoint PPT Presentation


  • 86 Views
  • Uploaded on

UPPER-LEVEL WINDS. Atmospheric pressure, temperature and winds at surface. Weather conditions. Atmospheric pressure and elevation. Winds at upper level (500mb = ~5600 m of elevation or 18000 feet). 1 knot = 1 “nautical” mile/h 1 knot = 1.15 MPH 1 knot = 1.85 km/h.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'UPPER-LEVEL WINDS' - ron


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

UPPER-LEVEL WINDS

Atmospheric pressure, temperature and winds at surface

slide4

Winds at upper level (500mb = ~5600 m of elevation or 18000 feet)

1 knot = 1 “nautical” mile/h

1 knot = 1.15 MPH

1 knot = 1.85 km/h

slide7

WINDS ALOFT

How does air move at higher elevations?

The gradient force INCREASES with altitude stronger winds

How does pressure changes with elevation?

slide8

H

L

H

L

L

H

800mb

warmer

colder

850mb

H4

800mb

H3

850mb

900mb

High

Height

H2

900mb

Low

Height

950mb

H1

950mb

Sea level

30° latitude

POLE (90°)

Pressure decreases with elevation:

SLOWER in WARMER air

FASTER in COLD air

Height (of pressure):

HIGH in WARMER air

LOW in COLDER air

Figure 5.17, Page 139

slide10

GEOSTROPHIC WIND

When the Coriolis force balances the gradient force.

The speed and direction of wind remain constant

It takes place at upper levels

geostrophic wind

slide12

GLOBAL CIRCULATION AT UPPER LEVELS

  • Weak equatorial easterlies (from ~ 25° to poles)
  • Tropical high pressure belts (15° -20°)
  • Upper air westerlies (from ~ 25° to poles, see undulations)
  • Polar low

(See Fig 5.19)

slide13

ROSSBY WAVES

  • Undulations of upper air westerlies
  • Formation:
  • Waves arise in region of contact between cold polar air and warm tropical air (Polar front)
slide14

ROSSBY WAVES FORMATION

2. Warm air pushes pole ward and a tongue of cold air is moved to south (undulation development)

3. Waves are strongly developed. Cold air are “troughs” of low pressure

4. Waves are pinched off, forming cyclones of cold air

slide15

ROSSBY WAVES

  • They are important for poleward heat transport
  • Reason for variable weather in midlatitudes
slide16

JET STREAMS

  • Regions at high elevation with strong wind streams
  • According to the World Meteorological Organization we can call a “jet stream” any speed exceeding:
  • 67mph, 58 knots, 108 km/h
  • The core of jet streams reaches ~102mph
  • They take place where atmospheric pressure gradients are strong

The greater the contrast in temperature, the stronger the jet streams blow

slide17

JET STREAM

  • Polar jet stream
  • Follows the edge of Rossby waves.
  • Found at 10-12 km elevation (33,000-40,000 ft)
  • Wind speed: 75-125 m/s (170-280 mi/hr)
  • 2. Subtropical jet stream
  • In the subtropical latitude zone
  • Speed 100-110 m/s
  • 3. Tropical easterly jet stream
  • In summer season, over Asia, India, Africa, only in Northern Hemisphere

Figure 5.21

slide18

JET STREAMS

  • Jet streams tend to be weaker in summer than in winter
  • Jet streams are less intense in the Southern Hemisphere due to smaller land masses
  • Strongest jet stream have been recorded during winter over Southern Japan (speeds up to 310 mph)