EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


Skypools on Surface Waves

March 30, 2022

IMG_8493

Photographer: Patti Weeks

Summary Author: Patti Weeks

Shown above is an abstract image containing distorted sunlit
reflections of the sky, clouds, and a fishing dock on a pond
stirred up by the wind. The optical result is a mixture of wavy lines,
swirls and a complex phenomenon called skypools. However, viewing
the picture from a different perspective, it could be said the abstract
photo looks like a landscape consisting of meandering rivers, oxbow
lakes, ponds, sandbars, and cliffs.

Skypools are seen as distorted swirls and pools on the surface of
gently moving bodies of water. The wind creates vibrational
surface waves that move the water up and down. From this motion,
crests and troughs are formed in the constantly changing curvature of
the water surface. We do not see straight line images, as normally seen
in the spectral reflection of a mirror, but instead diffuse
reflections are visible on the waves at various degrees of convex
and concave angles in addition to overlapping lines of sight from
point-to-point. The distorted images change from moment to moment,
meaning if another viewer at a different vantage point took a photo at
the exact same time as this photo, the image would be completely
different. Watch this video to see the motion of the ever-changing
skypools and distorted reflections. Skypools are generally seen when
the angle of the viewer’s sight is greater than 15 degrees, which
coincides with when most of the surface of the wave is visible. Only
when the wind stops can the water return to a relative state of
equilibrium. Photo taken on February 10, 2022.

Photo details: Apple iPhone 11 Pro; 6 mm, f/2, 1/122 second exposure,
ISO-32
* River Park North, Greenville, North Carolina Coordinates: 35.627,
-77.360

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Hydrology Links

* Current Sea Surface Temperature
* NOAA Ocean Explorer Gallery
* Ocean Color
* What is hydrology?
* Tides and Currents
* Water Resources of the United States
* World Waterfall Database
* The USGS Water Science School
* World Water Database
* The World’s Water
* USGS Surface Water Information Pages

-
Earth Science Picture of the Day is a service of the Universities
Space Research Association.

https://epod.usra.edu

--- up 4 weeks, 2 days, 21 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (21:1/186)

EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


Ice Crystal Formation on Frozen Soap Bubble

May 30, 2022


PatriciaR_IMG_0475a dusted cr 40 percent (003)

Photographer: Patricia Rasmussen

Summary Authors: Patricia Rasmussen; Jim Foster

There are several things of interest visible in this image of a frozen
soap bubble, which is approximately 1 in (2.5 cm) in diameter. The
soap bubble film is a sandwich made up of two soap layers with a water
layer in between. Colors near the central portion of the bubble are
likely due to diffraction processes -- light is interacting with the
thin soap film. Light waves are diffracted or scattered by the
varying thickness of the film in such a way that the waves interfere
with each other, creating regions of enhanced color (constructive
interference).

Frost crystals form in the water layer part of the bubble film; the
bubble itself is a hollow sphere. When photographing the crystals, the
depth of field is very shallow. So, the photographer chooses the place
where crystal growth is most active and the crystal pattern most
beautiful. Thus, the focus is either on the front or back wall of the
bubble. In this case, the back wall is prominent, while the growing
crystals on the front wall give a cloudy/hazy illusion to the image.
Note that as the bubble ages, the film becomes thinner, and the color
fades just before the bubble pops.

This photo was taken from my unheated garage on February 24, 2022. The
bubble is blown using a straw onto a base of snow, artificially
backlit, with some purple-tinted cracked ice for interest. "Bubblers"
say this is a highly addictive photographic subject because of the
seemingly infinite variables that cause the coloration and crystal
growth. It is! Click here to see a video of the crystals forming
between the inner and outer surfaces of the bubble. Notice in this
video that initially the crystals are rapidly swirling around the
bubble, likely from my breath as I blow through the straw.

Photo details: Canon 90D camera; F11; 1/250; 100 mm focal length; ISO
800. Post processing was general—levels, contrast, and a small crop.
* Eagle River, Wisconsin Coordinates: 45.9172, -89.2443

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Cryosphere Links

* Guide to Frost
* What is the Cryosphere?
* Bentley Snow Crystals
* Glaciers of the World
* Ice, Snow, and Glaciers: The Water Cycle
* The National Snow and Ice Data Center Google Earth Images
* Snow and Ice Crystals

-
Earth Science Picture of the Day is a service of the Universities
Space Research Association.

https://epod.usra.edu

--- up 13 weeks, 20 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (21:1/186)

EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


Roll and Lenticular Clouds Above Taiwan

June 30, 2022

DSC_7148(1)

Photographer: Wei-Chun Lin

Summary Authors: Wei-Chun Lin; Cadan Cummings

The photo above shows both a roll cloud (at far left) and lenticular
cloud (center of photo) as seen from a hilltop near Taipei, Taiwan. As
soon as I spotted satellite images showing the possibility of these
cloud structures, I rode my motorcycle to Yangmingshan National
Park near Taipei.

Roll clouds are a type of arcus cloud that form on the leading
edge of a storm. Unlike other shelf clouds, roll clouds are
separate from the thunderstorm base. This specific roll cloud was
still far away from the coast at the time of the photo. Their name
comes from their horizontal “rolling” motion.

Conversely, lenticular clouds are not related with storms. Instead,
these uniquely shaped clouds form when moist air cools and then
condensates as it passes over mountains. When the stable is forced
over the ridge, atmospheric waves are created that produce the
cloud’s characteristic lens-shape appearance. Click here for a
time-lapse video of the clouds.

Photo details: Nikon D850, f/11, 1/500 second exposure, 24mm
* Taipei, Taiwan Coordinates: 25.033, 121.565

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Kelvin-Helmholtz Wave Clouds Over Taipei
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Cloud Links

* Atmospheric Optics
* The Cloud Appreciation Society
* Cloud Atlas
* Color and Light in Nature

-
Earth Science Picture of the Day is a service of the Universities
Space Research Association.

https://epod.usra.edu

--- up 17 weeks, 3 days, 21 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (21:1/186)

EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


Mature Snapdragon Flowers Remain Closed

July 29, 2022

Menashe_snapdragon1a

Menashe_snapdragon2

Photographer: Menashe Davidson

Summary Author: M enashe Davidson

The time of flower opening marks the onset of a period in which
pollinators are attracted by the flower sweetness, leading a pollen
removal and pollination. In many species the flowers are open
permanently, whereby the opening period is terminated by a closure
movement, or by petal withering or abscission. But there are few
species, such as snapdragons, where mature flowers stay closed.

Snapdragons (Antirrhinum majus, family Plantaginaceae) have a wide
range of flower colors, and they’re easily grown in gardens. The
snapdragon flowers are closed flowers (top photo) with two modified
petals, described as lips, that essentially prevent honeybees from
penetrating them. Note, however, that the flowers can be opened when
they're pressed on their sides (bottom photo). Here we can see the
inside of the flower, where there are four stamens with white
filaments surrounding a pistil (green stalk). Bumblebees, which
are much bigger than honeybees, are the main pollinators for
snapdragons because they’re larger size permits them to open the closed
flowers. Photos taken in March 2022, from my home garden in Rishon
LeZion, Israel.


Rishon LeZion, Israel Coordinates 31.9730, 34.7925


Recent EPODs

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Earth Science Picture of the Day is a service of the Universities
Space Research Association.

https://epod.usra.edu

--- up 21 weeks, 5 days, 21 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (21:1/186)

EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


Hollow Stems in Amaryllis belladonna

August 30, 2022

Menashe_Stems

Menashe_Stems2

Photographer: Menashe Davidson menashe.davidson@gmail.com

Summary Author: Menashe Davidson menashe.davidson@gmail.com

While in my home-garden (in Rishon LeZion, Israel), I observed the
erect hollow leafless stems of Amaryllis belladonna plant, also
known as the Amaryllis lily and the August lily. Carrying
inflorescences they bear showy funnel-shaped flowers (1st photo). I
questioned the purpose of why there are hollow stems in some plants.
Stems of course provide a transport system, mechanical support, and
a primary growth point for plant. They also improve the presentation of
the plant’s sexual organs, thereby increasing the plant's chance of
reproduction.

The common misconception was to believe that the hollow stem is solely
for nutrient or water transport. But when I cut the stem in various
heights, I learned that the hollow stem holds water only in the bottom
4 or 5 inches (12 cm) -- most of the stem contains air (2nd photo).

Scientists In University of Guelph (Ontario) studied differences in
plant stem type, and how effectively they regulate their temperature.
They found that the stem lumen (hollow portion of the stem) allows the
plant to maintain a distinct internal microclimate and in the present
of sunlight, the temperature in the lumen was slightly above that of
the ambient air. Increases in temperature encourages growth of sexual
organs in plants, which in turn helps the flower to develop quickly,
becoming more prominent to pollinators. And this effect is exactly what
I observed in Amaryllis flowers. (Below)

Menashe_Stems3


Rishon LeZion, Israel Coordinates: 31.9730, 34.7925


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-
Earth Science Picture of the Day is a service of the Universities
Space Research Association.

https://epod.usra.edu

--- up 26 weeks, 1 day, 21 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (21:1/186)

EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


Basket Stinkhorn

September 30, 2022

Stinghorn

Photographer: Mila Zinkova
Summary Author: Mila Zinkova

Shown above is the Basket Stinkhorn, Clathrus ruber, that I came
upon during a walk in the woods not far from San Francisco, California.
Its odor is repugnant to you and I but is evidently like catnip to
flies. " They flock to her foetid scent, feed upon the
spore-impregnated greenish-black gleba, and soar off, spreading
stinkhorn spores in their wake."

Most often found in temperate deciduous forests, Clathrus ruber
hatches from an egg-like film. At the base of which is a mycelial
“root,” that at this stage has little scent and might be edible to
some. However, it doesn’t take long before its stench is so
overpowering that only a creature like a fly could be attracted to it.
Click here to see a video from hatching to decaying.



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Plant Links

* Discover Life
* Tree Encyclopedia
* What are Phytoplankton?
* Encyclopedia of Life - What is a Plant?
* USDA Plants Database
* University of Texas Native Plant Database
* Plants in Motion
* What Tree is It?

-
Earth Science Picture of the Day is a service of the Universities
Space Research Association.

https://epod.usra.edu

--- up 30 weeks, 4 days, 21 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (21:1/186)

EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


On the Wind: Plant Seed Dispersal

November 30, 2022

Menashe_windandseeds_Picture1

Photographer: Menashe Davidson

Summary Author: Menashe Davidson:

Seed dispersal is an adaptive mechanism in all seed-bearing plants,
participating in the movement or transport of seeds away from their
parent plant to ensure the germination and survival of at least some of
their seeds. It can take many forms, yet most dispersal mechanisms fall
within the categories of gravity, wind, water, and animal
dispersal. Species that use wind dispersal have a windsail-like
structure, called the "pappus," that generally opens and closes in
response to moisture. On dry, windy days the pappus opens, catches
the wind, and transports the seeds far away.

Shown in the collage above are images of seeds, and pappus, of 4
different species of plants, from different habitats. All of them have
the same purpose – to transport the seeds far away from the mother
plant.
1. Nerium oleander - Oleander, Bush, Public area, taken January
2016
2. Adenium obesum - Desert rose, Ornamental, Home-garden, taken
January 2019
3. Stephanotis floribunda - Madagascar Jazmin, Ornamental climber,
Home-garden, taken June 2022
4. Araujia sericifera - Moth plant, Invasive vine, Citrus
plantation, taken August 2017

Click here to see a video of Gone with the Wind, taken from my home
garden in Rishon Le Zion, Israel.


Rishon Le Zion, Israel Coordinates: 31.9730, 34.7925


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Plant Links

* Discover Life
* Tree Encyclopedia
* What are Phytoplankton?
* Encyclopedia of Life - What is a Plant?
* USDA Plants Database
* University of Texas Native Plant Database
* Plants in Motion
* What Tree is It?

-
Earth Science Picture of the Day is a service of the Universities
Space Research Association.

https://epod.usra.edu

--- up 39 weeks, 2 days, 21 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (21:1/186)

EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


Crepuscular Rays Observed from Italian Alps

December 30, 2022


Tramonto sull'Aiguille Noire de Peuterey

Photographer: Valter Luna

Summary Authors: Valter Luna; Jim Foster

Shown above is a breathtaking set of crepuscular rays that I
observed over the Aiguille Noire de Peuterey in the Italian Alps.
Rays such as this while most often associated with clouds near the
horizon can also take shape when sunlight filters through mountain
passes, as was the case on this mid-summer’s evening. However, for
these rays to be seen, the atmosphere must be dusty. Sunlight
scattered by dust particles, and or other aerosols suspended in
the atmosphere, act to project the rays across the sky. Photo taken on
July 29, 2022.

Photo details: Nikon D100 camera; Sigma lens 18-250 mm (18 mm); 1/250
sec exposure; f / 16; ISO 200


Aiguille Noire de Peuterey, Italy Coordinates: 45.815, 6.893611


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Atmospheric Effects Links

* Atmospheric Optics
* Optic Picture of Day: Gruppo Astrofili Galileo Galilei
* Color and Light in Nature
* The Colors of Twillight and Sunset
* Refraction Index
* Image Gallery: Atmospheric Effects
* What is a Rainbow?

-
Earth Science Picture of the Day is a service of the Universities
Space Research Association.

https://epod.usra.edu

--- up 43 weeks, 4 days, 20 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (21:1/186)