Visible Imagery

Visible full disc image. Note circulations in both Northern and Southern hemispheres, ITCZ, and moon in background.

In this North American visible sector, note the effects of parallax error with distance form the satellite sub-point.

Visible imagery is analyzed in terms of brightness and texture. Deeper, more vertically developed clouds such as these thunderstorms over the mid Atlantic region appear very bright while lower, thinner clouds are grayer. Also note the very lumpy texture to the convective cloud tops vs nearby stratified clouds along the PA/MD border.

Infra red (IR) imagery

IR imagery senses cloud top temperatures. Here brightness correlates to colder cloud tops usually a function of cloud top altitude.

IR North American sector. Note deep cyclone over western Ontario just NW of lake Superior.

Another IR image of North America from the GOES E satellite. Note effects of parallax in infra red.

Enhanced IR images apply a color scheme to various temperature ranges. In this image of hurricane Ike at category 5 intensity, the deepest convection and thus, coldest cloud top temperatures are in red and dramatically highlight the hurricane’s eye wall.

Note the differences in land vs water temperatures in this nighttime IR image. The dark specks are lakes, large rivers and reservoirs. The Great Lakes are also contrasted well against the adjacent cold land mass.

Though poorer in resolution than visible imagery, smaller scale features can also be identified in IR.

This IR image can fool you. Focus on eastern Kansas. Note the darker, warmer area over SE Kansas and S Missouri are areas of fog and low stratus. The top of this cloud deck is warmer than the surrounding ground temperatures where skies are clear and there has been greater radiational cooling.

Fog and stratus

Note sharp, dendritic pattern to this river fog over the MS and lower WI river valleys. Also note the long lived contrails over eastern WI.

A polar orbiter view of valley fog in the Appalachians. Note the dendritic pattern produced by topography.

Determining stability and wind flow

With unstable, cumuliform clouds, wind flow will be parallel to cloud “streets”.

In the case of stable, stratiform cloud bands, or wavelets, wind flow is perpendicular to the cloud bands.

Guess the wind direction over the western Great Lakes.

Note the wave pattern in this cold advection stratocumulus deck. What can be said about the wind direction and speed?

The lack of cloud growth can also indicate wind direction and, in some cases, speed as well. Note the clearing from the Door peninsula of WI, southward through NE IL, NW IN and W lower MI as winds turn onshore from Lake MI bringing cooler, stable air inland.

Polar air flowing across the Great Lakes often produces lake effect clouds and snow squalls. What was the direction of wind flow over the upper Midwest on this day?

Cumulus streets vs clear sky or wave clouds highlight areas of instability such as in the air feeding this thunderstorm complex moving through the Chicago area.

Satellite imagery can also be very useful in getting a fix on the position of frontal boundaries, such as this warm front advancing across the southern Great Lakes.

Other surface features

Snow cover. Note river valley pattern over the Midwest and mid Atlantic.

Note the river pattern in the snow cover over the Midwest, the frozen lakes over MN, and even the change in vegetative cover over WI.

A zoomed in view of snow cover over northern IL.

An IR view of the same area on 1/1/06. Note the fires and downstream smoke plumes. This gives a good idea of what the wind flow is like over the southern Plains.

Thunderstorm features

Note the transverse bands along the edge of the anvil canopy of this deep convective complex over Iowa. What does this infer in terms of turbulence?

Look at the overshooting tops boiling up through the anvil canopy of this severe thunderstorm complex. Note also the wavelets in the anvil downstream over AR and MO. These are a good example of gravity waves and are known to be associated with severe turbulence.

Turbulence ( CAT )

Wind barbs superimposed on water vapor imagery (kind of like a type of IR imagery). The dark area running N – S through the Plains states is the dry slot associated with an occluding mid latitude cyclone. This is a good way to locate the jet stream axis and its associated CAT.

Visible image of a cyclone centered over the NW corner of KS. Note the comma cloud pattern.

This low sun angle visible image highlights the 3 cloud decks associated with a mature extra tropical cyclone and its deformation zone. Deformation zones are also areas of severe CAT.

A good example of mountain wave turbulence (MWT) as indicated by satellite imagery.

An IR image of MWT downstream of the Rockies.

Extra tropical cyclones

A nice enhanced IR image of a fully occluded cyclone departing the Great Lakes region. Note the temperatures of the 3 main cloud decks of the cyclone: The jet stream cirrus deck, the comma head deck, and the cold advection stratocumulus (wrap around) deck.

Visible image of a maturing comma cloud system over the Plains.

A smaller, more compact cyclone centered just south of the Quad Cities. Note the tight cyclonic curvature to the cloud elements.

A zoomed in view of the previous image.

An enhanced IR view of the cyclone center SSW of KMLI. Note the colder cloud tops associated with cyclonically curved convective elements over IL.

An IR view of a mid latitude cyclone. Note the brightness of the convective tail portion of the comma cloud (over the mid and lower MS valley), indicating explosive squall line development.

Another IR image of a maturing cyclone.