Web materials shown in class

Plus other related items of potential interest

• Excellent illustrations and brief explanations (continued across multiple pages) on sea breezes and land breezes and why they occur from UIUC weather world 2010 project
• Influence on coastal cloudiness and precipitation and 6hr satellite movie (gif, 4.6Mb) at coast of North Carolina showing sea breeze front
• 12hr visible satellite movie (mpg, 4.9Mb) over South Florida where thunderstorms triggered with help from sea breezes

• Some information on monsoons and a little on their impacts.
• Recent news on monsoonal flooding in south Asia and China.

• Explanation and model simulation from UCLA
• Large-scale weather pattern that causes them

• 500-mb level heights and temperatures - Initially the flow is generally zonal (though with something of a trough over the west) and along the temperature contours meaning there is little temperature advection. Then the trough intensifies and over the central US the flow is from warmer toward colder air, advecting warm air northward. This continues as the system moves northeastward until near the end the system weakens and the temperature gradients become smooth again.
• Sea level pressure (SLP) and 300-mb (~jet stream) level heights - Again initial a weak trough is evident over the west. Surface low just ahead of the trough axis is in prime location to intensify, and it does as the upper trough gets stronger and the system moves northeastward. The system is at its most intense when the upper-level and surface low centers are co-located, then it begins to dissipate.
• SLP and 500-mb level heights - Similar progression to that seen on SLP/Z300 maps
• SLP, near-surface temperature, and 500-mb level heights - Note surface warm air advection ahead of developing system. See how the warm sector gradually gets pinched off from the low pressure center. Once this energy source is cut off the system dissipates. Also notice through the progression the southward advection of cold air behind the system.
• SLP, near-surface temperature, and IR satellite images - Initially the cloud formations with the system are amorphous. But as the system develops and reaches its mature stage it has the idealized comma shape - clouds wrapping around the backside at the low center, a broad cloud shield ahead of the warm front, and a line of showery clouds along and just ahead of the cold front.

• Surface map - Low pressure center over Kansas with trailing cold front (already becoming occluded). No warm front is shown, but notice the cold front that trails down near the cyclone from off the map east of Maine from another system. The high pressure and colder air from this other system are centered just south of Hudson Bay, and a stationary front at the Canadian Rockies denotes the edge of this air mass held in place by the terrain. The weather observations around the Great Lakes are consistent with the situation if the cold front there was actually a warm front moving the opposite direction.
• Satellite images - Rotation and comma shape to mid-lat cyclone clearly evident
  • Visible: West | East - Note the clear slot around the low center, which indicates drier air from the cold sector is being pulled in as the system is losing its link to the warm air that provides its energy.
  • Infrared: West | East - The clouds along the trailing cold front are dark gray indicating they are low. The warm air rises up ahead of the system.
  • Water vapor: West | East - Another view of dry, cold air aloft that weakens the system.
• 500-mb level heights - At upper levels the low pressure center is cut-off. Note the trough associated with the other system over southeast Canada.
• 1000-mb level heights (approximately same as sea level pressure) - Surface low in same spot as upper low, which indicates the storm has peaked. The warm sector covers most of the eastern US. The older front is clearly visible around the Great Lakes, and the surface pressure is high where the air is coldest.
• 500-mb to 1000-mb layer thickness (measure of average layer temperature) - Streamlines show warm air from the Gulf of Mexico moving northward into the low center and up to and along the fronts. Air moves clockwise and outward from the high pressure center in Canada. Convergence at the front lead to precipitation there.
• 700-mb level vertical motion - Upward motion and greater likelihood of precipitation where yellow and orange. Picture is very splotchy. Vertical velocity and precipitation are difficult to forecast with fine resolution.