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.


Birds on the Move

February 10, 2020

Storni-di-Stormi

Photographer: Marco Meniero
Summary Author: Marco Meniero

Shown above are images of flocks of starlings as observed earlier
this winter from the Viterbo Airport Control Tower in Viterbo, Italy.
Even if you live in the city, you’ve likely noticed the choreography of
bird flocks (most likely starlings or pigeons) as they twist and
turn across the sky. But what drives their movements? How do they
coordinate with their feathered flight companions? Why is it that
birds of a feather flock together?

In a study published several years ago in the Proceedings of
the National Academy of Sciences, researchers from the University
of Warwick suggest that these birds move in such a way as to achieve
the maximum density allowing them to still have a good view of their
surrounding space. This will occur they receive light from many
directions, a condition known as marginal opacity. It seems to be
that changes in the relationship between shadow and light alert the
birds to fly in such a way to achieve this. The scientists decided to
test their hypothesis using a computer simulation.

Virtual starlings were therefore been programmed to follow their
closest companion and move to the area of the flock from which they
have access to the greatest amount of information. The results of the
experiment showed that programmed in this way, the virtual starlings
join in compact groups and move in a way that’s superimposable to how
real starlings are observed to fly. Note also the rose-colored Belt
of Venus and the rising of the Earth’s shadow. Photo taken on January
15, 2020.
* Viterbo, Italy Coordinates: 42.4207, 12.1077

Related EPODs

Birds on the Move Crown-of-Thorns Starfish Encore - Spider
Webs in Dominican Amber Archive - Feeding Frenzy Water Droplets
on a Spider's Web on the Viterbo Airport Control Tower Exoskeleton
of Cicada
More...

Animal Links

* Animal Diversity Web
* ARKive
* BirdLife International
* Bug Guide
* Discover Life
* Integrated Taxonomic Information System
* Microbial Life Resources
Earth Science Picture of the Day is a service of the
-
Universities Space Research Association.

https://epod.usra.edu

--- up 2 weeks, 5 days, 15 hours, 5 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.


La Palma Shadow Projection at Sunset

March 10, 2020

PANORAMICALAPALMA5-2

Photographer: Roberto Martín Pérez
Summary Authors: Roberto Martín Pérez; Jim Foster

Shown above is the projection of the shadow of the island of La
Palma ( Canary Islands, Spain) on the distant atmosphere. The
Roque de Los Muchcachos Observatory is at far left. Mountain
shadows such as this can appear if the lower atmosphere is
dusty. In this case, it’s likely that easterly winds are
blowing dust from the Sahara Desert over the Canary Islands. Note
the triangular shape of the shadow. Even the shadow of a relatively
flat-topped ridge will look pointed because of the viewer’s
perspective. Portions of the islands of Tenerife and La Gomera can
be seen in the background at right. Photo taken on February 2, 2020.
* Isla de La Palma, Spain Coordinates: 28.7134, -17.9058

Related EPODs

La Palma Shadow Projection at Sunset Captivating Sunrise from
Portland, Oregon Halo Formation above Cadini di Misurina, Italy
Encore - Upper Tangent Arc, Halo, Sundogs and Glitter Path Observed
from Vancouver Encore - Fogbow Near Mount Luxmore, New Zealand
Corona Over Westmoreland State Park, Virginia
More...

Atmospheric Effects Links

* Atmospheric Optics
* 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 6 weeks, 6 days, 14 hours, 5 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.


Lunar Halo Observed from Saxony, Germany

April 10, 2020

Ring-Fb

Photographer: Heiko Ulbricht
Summary Authors: Heiko Ulbricht; Jim Foster

A few weeks ago, my gaze was attracted toward the waxing gibbous
Moon because of this impressive halo that surrounded it. 22-degree
lunar halos, though not rare, are always a treat to see. The one
featured above was observed over Opitz Hill in Saxony, Germany.
Moonlight shining through the randomly oriented ice crystals that
compose the cirrostratus clouds, fully covering the sky here,
resulted in this beauty. Photo taken on March 5, 2020.

Photo Details: Canon EOS 6D camera; 2.8/12 mm Fisheye lens; ISO 200;
3-second exposure.
* Saxony, Germany Coordinates: 51.026944, 13.358889

Related EPODs

Lunar Halo Observed from Saxony, Germany Encore - Northern
Lights Above Norway Frost Crystals on Airplane Window Rainbow
Closeup on Evia Island, Greece Encore - Sunset Rainbow Over Samos
Island, Greece Sunrise Pillar and Upper Tangent Arc
More...

Atmospheric Effects Links

* Atmospheric Optics
* 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 11 weeks, 2 days, 14 hours, 5 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.


Solar Halo Over Thessaloniki, Greece

June 10, 2020

αλως44sat

Photographer: Christina Irakleous
Summary Authors: Christina Irakleous; Jim Foster

Featured above is an amazing 22 degree halo I observed above
Thessaloniki, Greece, during the late morning on April 16, 2020. A
contrail nearly bisects the solar disk – its shadow is just below
it. Ice crystals that compose cirrus type clouds are
responsible for such halos. If they’re randomly oriented, the
crystals refract sunlight in such a way to form a circle. More colorful
halos result if crystal sizes are larger than average (approximately
0.1 to 0.2 mm across). Note that a streetlight is used here to block
the light of the Sun. Always use extreme caution anytime you
look anywhere near the Sun.

Photo Details: Camera: Canon EOS 600D; Software: Adobe Photoshop CS5
Windows; Exposure Time: 0.0003s (1/4000); Aperture: ƒ/5.6; ISO
equivalent: 100; Focal Length: 18.0mm.
* Thessaloniki, Greece Coordinates: 40.6401, 22.9444

Related EPODs

Solar Halo Over Thessaloniki, Greece Encore - Development of a
Lightning Strike One View, Four Rainbows Anticrepuscular Rays
and Lunar Eclipse Encore - Summer Lightning in Florida Twilight
Times: Civil, Nautical and Astronomical
More...

Atmospheric Effects Links

* Atmospheric Optics
* 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 20 weeks, 16 hours, 4 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.


Crucial Corbiculae

July 10, 2020

DSCN7136 crop1

Photographer: Rob Sheridan
Summary Author: Rob Sheridan

Traveling by boat with Virginia colonists, hives of European
Honeybees ( Apis mellifera) first arrived in North America in the
early 1600s. Escapees rapidly colonized the new country and became
critical natural pollinators serving the expanding agricultural
society. They continue to provide this important service for the
nectar (a source of energy) and pollen (a source of protein)
that they bring back to their beehive. Nectar is extracted via a
proboscis and becomes the main ingredient of honey. Pollen collects
on the bee’s body hairs, is moistened with saliva, pushed into
corbicula ( pollen baskets) and flown to the hive, where it
becomes the main ingredient of bee bread (the primary source of
protein for the hive’s brood).

This photo shows a European Honeybee entering a common milkweed
flower for nectar. This may be its last stop before returning to the
hive, as its pollen baskets are full! Photo taken on July 1, 2019.
Photo Details: Camera - NIKON COOLPIX AW120; Software - Windows Photo
Editor 10; Exposure Time - 0.0010s (1/1000); Aperture - ƒ/4.4; Focal
Length (35mm) - 61.
* Squantum Massachusetts Coordinates: 42.2948, -71.0104

Related EPODs

Crucial Corbiculae Bioluminescence off Southern California
Encore - Diatom Colony Superb Camouflage of the Crab Spider
Magpie Feather Coloration Wild Horses Along the Pony Express
Trail
More...

Animal Links

* Animal Diversity Web
* ARKive
* BirdLife International
* Bug Guide
* Discover Life
* Integrated Taxonomic Information System
* Microbial Life Resources
Earth Science Picture of the Day is a service of the
-
Universities Space Research Association.

https://epod.usra.edu

--- up 24 weeks, 2 days, 16 hours, 4 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.


Anticrepuscular Rays and Alpenglow

August 10, 2020

Ragggi anticrepuscolari venas copia 2

Photographer: Marcella Pace
Summary Author: Marcella Pace

Rays that converge behind a mountain make us believe that the Sun
is behind it, but it’s not in this case. Here, though the mountain peak
is illuminated by the Sun, it’s in front of it not behind it. How is
this possible? Anticrepuscular rays! These rays appear on the
opposite side of the Sun at sunset (or sunrise) and seem to converge on
the horizon opposite the true position of the Sun, creating the
illusion that the Sun is at the point where they converge.

Anticrepuscular rays, in reality, are parallel and cross the entire
celestial vault from west to east. Perspective makes it appear
that they converge. They’re an extension of crepuscular rays, even
if the latter don’t always manifest themselves or are clearly visible
at the same time. I’ve noticed that, unlike the crepuscular rays, it
seems that the alternation of the shadow rays of the anticrepuscular
rays is wider than the rays of light as if the fan of the
anticrepuscular rays was the negative of the crepuscular rays.

This photo was taken just before sunset on May 14, at Valle di
Cadore (Belluno), Italy. The mountain peak is part of the Dolomites
-- a World Heritage Site. Note that the top of the mountain is
still illuminated by the Sun, creating an Enrosadira or Alpenglow
effect.

Photo Details: Nikon D7100 camera; 18mm; 1/15 second exposure; f/7,1;
ISO 100. Taken at 5:21 p.m. on May 14, 2016.
* Valle di Cadore, Italy Coordinates: 46.4098, 12.2974

Related EPODs

Anticrepuscular Rays and Alpenglow Bolt over Dehradun, India
Spray Droplets and Rainbow Colors Earth Rainbow Changes in
Istanbul Seascape from Morning to Afternoon Crepuscular Rays Off La
Palma, Canary Islands
More...

Atmospheric Effects Links

* Atmospheric Optics
* 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 3 weeks, 4 days, 15 hours, 25 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.


EPOD 20th - The Puddling of Butterflies

September 09, 2020

DSC02971 2 DSC02991 2
August 2019 Viewer's Choice We’re celebrating 20 years of Earth
Science Picture of the Day during the month of September! Today’s photo
features a popular EPOD from the past. Thanks to all of our followers
(on the blog, Facebook, Instagram and Twitter) for supporting us.
Thanks also to all of you who’ve submitted your photos. We’re most
appreciative. This EPOD was originally published August 26, 2019.

Photographer: Patti Weeks
Summary Author: Patti Weeks

On a recent trip to the Great Smoky Mountains National Park I took
a side trip to the less frequented Cataloochee Valley region on the
east side of the park in North Carolina. While elk, reintroduced in
2001, are the area’s main attraction, they were staying cool in the
woods beside the open meadows in the middle of this hot summer day.
However, much to my delight, the edges of the gravel road were teeming
with butterflies, intent on the damp mud.

In my research, I discovered that some Lepidoptera (butterflies and
moths) do what’s referred to as puddling or mud-puddling. While
I only saw the butterflies near puddles or on damp pebbles, some
species can also absorb nutrients from dung and carrion or even sweat
on human skin. It’s primarily the males that participate in this
behavior in order to ingest salts and amino acids to fortify their
sperm, aiding in their reproductive success. The extra nourishment
passed to the female ensures egg survival.

I saw three distinct butterfly species: eastern tiger swallowtails
(yellow), pipevine swallowtails (dark blue), and the small
Appalachian azures (light blue). Thanks to the extensive research
of biologist and expert lepidopterist Jeff Pippen, via his website
and email confirmation, I was able to narrow his list of nine
similar-looking azures (among his list of over 50 blues) to the
Appalachian azure.

The kaleidoscope, swarm, or flutter (three of the terms for a
collective of butterflies) of each of these three butterfly species was
so focused on the puddling activity, that they weren’t at all disturbed
by approaching photographers or slowly-moving vehicles. Although each
species generally stayed together, they shared some of the same
locations. Click here to see a video of fluttering azures above
some of the puddling butterflies. Photos taken July 5, 2019.

Photo Details: Top - SONY DSC-HX400V camera; 44.98 mm focal length;
f/5; 1/320 second exposure; ISO 80. Bottom - Same except 29.44 mm focal
length; f/4.5; 1/200 sec. exposure; ISO 320.
* Cataloochee Valley, North Carolina Coordinates: 35.6401,
-83.0801

Related EPODs

EPOD 20th - The Puddling of Butterflies Leafcutter Bee
Crucial Corbiculae Bioluminescence off Southern California
Encore - Diatom Colony Superb Camouflage of the Crab Spider
More...

Animal Links

* Animal Diversity Web
* ARKive
* BirdLife International
* Bug Guide
* Discover Life
* Integrated Taxonomic Information System
* Microbial Life Resources
Earth Science Picture of the Day is a service of the
-
Universities Space Research Association.

https://epod.usra.edu

--- up 2 weeks, 2 days, 20 hours, 20 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (21:1/186)