Atmospheric Effects Part 2

Sunbeams and Shadowbeams

Sunbeams and Shadowbeams

• Sunbeams; shafts of light made visible in dust/moisture laden atmosphere
• occur in rare conditions which must be met in the painting if you want them to be convincing
• 3 conditions: 
• a high screen of clouds, foliage, or architecture is punctured by a few openings
• air is filled with dust, vapor, smoke, or smog
• the view is towards the sun
• sunbeams usually shine through uneven apertures
• using traditional paint, brush a light, semi opaque tone over the dry background where the beams appear
• Shadowbeams
• occur most often when a jet contrail aligns with the line of sight
• the darker beam is usually only visible when there is a light, hazy sky behind it
• both sunbeams and shadowbeams should be used sparingly because they attract a lot of attention

Dappled Light

Dappled Light

• as sunlight passes through the upper leaves of a tree, it covers the ground with circular spots of light
• each space acts as a pinhole projector
• the spots of light vary in size depending on how high the projecting canopy is above the ground
• high canopy = larger circles with softer edges

Cloud Shadows

Cloud Shadows

• tool you can use to control the viewer's attention
• position the light wherever you want to draw interest
• adds variety to dull expanses of land
• 3 rules;
• margin between the light and shadow must be a soft edge
• size and spacing must match up with the clouds in the sky
• shadow area is darker and cooler, but the shadow does not have much of a blue cast as do the cast shadows on a clear day
• tip; run a cool, gray wash across the whole shadowed region to key it down
• or paint the whole scene as if it were first in shadow and define the lit area last

Illuminated Foreground

Illuminated Foreground

• put the foreground in light, load it with detail and then throw the middle distance into shadow

Snow and Ice

Snow and Ice

• snow is denser than clouds, so it is whiter
• picks up the colors of everything around it (especially in shadow)
• cast shadows on snow take on the color of the sky
• example:a blue sky makes blue shadows
• lots of subsurface scattering
• as snow ages and compacts, it becomes darker
• as ice crystals get larger, the snow develops a more specular reflection, becoming shinier in certain places

Water Reflection and Transparency

Water: Reflection and Transparency

• water only approaches the reflectivity of a mirror only when you are looking straight across its surface
• the reflection of a light object in water will appear slightly darker than the object itself
• parts of a river can be darker because the reflected light from the sky is blocked by the mass of rock
• behavior of dark objects in water depend on: 
• amount of sediment in the water
• amount of light shining into the water
• if water is dirty, the darks will lighten and turn browner
• images become distorted by wavelets on the water
• vertical lines are preserved in the reflection
• if the water is clear, shadows cannot cast a shadow over deep water
• if the water is filled with sediment, cast shadows are more apparent

Mtn Streams

Mountain Streams

• mountain streams behave differently than lowland streams and lakes
• water is clearer, moves with velocity
• stones shift to darker, warmer colors
• colors get more blue when it is deeper than 3 ft
• underwater forms can be painted with a degree of looseness
• colors are warmer in shallow areas
• Foam should be painted last

Color Underwater

Color Underwater

• at great depths, only violet and ultraviolet light remain
• bright red objects becomes more dull
• flashes of light restore color deep underwater
• in the distance, objects have lost most of their contrast and nearly match the ocean color