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.


Altocumulus Wave Clouds Over Melkbosstrand, South Africa

January 23, 2020

IMG_20200106_155311 (1)

Photographer: Amanda Pollard
Summary Authors: Amanda Pollard; Jim Foster

These altocumulus wave clouds were observed over Melkbosstrand,
Cape Town, South Africa on January 6, 2020. Wave clouds take shape when
stable air is forced to rise. Most often a mountain range is
the forcing mechanism, but even a series of hills may be sufficient to
initiate lifting. Oscillation of winds aloft caused by a topographic
barrier sets up a train of lee waves, known as stationary gravity
waves. When air moving over such a barrier moves upward and crests,
adiabatic expansion cools and condenses the water vapor within
the air, forming a visible cloud. The oscillating air then sinks
downward to an altitude (temperature and barometric pressure) where the
vapor evaporates, so the cloud dissipates. This cycle is repeated
as long as the air moves in a wave-like fashion, often resulting in
eye-catching cloud trains or in this case, cloud fingers. The
wavelength (distance from one crest to another or one cloud to
another) is determined by a number of factors including wind speed,
altitude of the waves, and stability of the atmosphere.

Photo Details: Camera: HUAWEI ANE-LX1; Exposure Time: 0.0004s (1/2604);
Aperture: ƒ/2.2; ISO equivalent: 50; Focal Length (35mm): 26.
* Melkbosstrand, South Africa Coordinates: -33.705342, 18.465253

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Altocumulus Wave Clouds Over Melkbosstrand, South Africa Frozen
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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 1 day, 15 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.


Archive - Gneiss Outcrop in Montana

February 23, 2020

Gneissbarnes (2)

Each Sunday we present a notable item from our archives. This EPOD was
originally published February 25, 2014.

Photographer: Lindsey Barnes
Summary Author: Rod Benson
This outcropping of gneiss is located in a cirque called
Beehive Basin, about 35 mi (56 km) south-southwest of Bozeman,
Montana. Gneiss is a metamorphic rock that forms when
sedimentary rock (such as shale) or igneous rock (such as
granite) is changed by heat and or pressure and in some cases even
by chemically active fluids.
Gneiss makes up most of the lower portion of Earth's continental
crust -- very old material referred to as basement rock. In
most places, basement rock is covered with younger sedimentary rocks.
However, drill down far enough anywhere on a continent and you’ll
usually strike gneiss. In fact, the rock that makes up the mountains in
southern Montana, including the gneiss in the photo, are among the
oldest in the state -- formed during the Archean Eon over 2.5
billion years ago. Here, blocks of crust were forced upward and many of
the younger rock formations eroded away, exposing the basement rock.
Today this gneiss makes up many of the mountains in and around Montana,
including the Beartooths, the Tobacco Roots and a significant
portion of the mountains in between. Photo taken on January 18, 2014.
* Beehive Basin, Montana Coordinates: 45.331608, -111.395211

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British Columbia Encore - Tufa Formations at Winnemucca Dry Lake,
Nevada Archive - Sulfur Sandstone Towers Landmannalaugar,
Iceland
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Geology Links

* Earthquakes
* Geologic Time
* Geomagnetism
* General Dictionary of Geology
* Mineral and Locality Database
* Mohs Scale of Mineral Hardness
* This Dynamic Earth
* USGS
* USGS Ask a Geologist
* USGS/NPS Geologic Glossary
* USGS Volcano Hazards Program

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

https://epod.usra.edu

--- up 4 weeks, 4 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.


Pomez Stone Field

March 23, 2020

IMG_20200211_233633_063 (1)

Photographer: Emanuel Vásquez
Summary Authors: Emanuel Vásquez; Jim Foster

The landscape featured above, part of the Atacama Plateau in
northwestern Argentina, is characterized by an extensive accumulation
of pumice, which after tens of thousands of years of physical
erosion has acquired its present-day morphology. The very high
elevation (average elevation of 14,800 ft or 4,500 m) and dry climate
of the Pomez Stone Field helped create this unusual plateau
landscape. Because the plateau is subjected to considerable diurnal
thermal amplitude, frequently 35 degrees F (20 C) or more between the
daily maximum and minimum temperatures, freeze-thaw cycles
accelerate erosion rates. Photo taken on February 8, 2020.

Photo Details: Camera: Nikon D750; Lens: Sigma 70 200; Exposure Time:
1/4000); Aperture: ƒ/2.8; ISO equivalent: 50.
* Pomez Stone Field, Argentina Coordinates: -26.65972, -67.51417

Related EPODs

Pomez Stone Field Archive - Tutukaka Coast From Frying Pan
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Geography Links

* Atlapedia Online
* CountryReports
* GPS Visualizer
* Holt Rinehart Winston World Atlas
* Mapping Our World
* Perry-Castañeda Library Map Collection
* Types of Land
* World Mapper

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

https://epod.usra.edu

--- up 8 weeks, 5 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.


Protandry Phenomenon in Hollyhock Plants

June 23, 2020

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Photographer: Menashe Davidson
Summary Author: Menashe Davidson

Alcea setosa ( Bristly Hollyhock) is prominent in springtime in
the Middle East, due to its impressively colored and large flowers that
are arranged along a conspicuous inflorescence stalk. This beauty
triggered me to collect seeds from plants growing in the wild. I then
grow them in containers in my apartment garden in Rishon LeZion,
Israel, as shown above.

I keep track of them on a daily basis so as to consider all stages of
their development. The flowers come in a variety of colors, typically 1
to 4 inches (2.5 to 10 cm) apart. Their blooms start at the bottom of
the stem and spiral upward. About every 1-3 days a new flower opens in
the spiral on the same stem and stays open a few days.

The Hollyhock is a hermaphrodite plant; the flower possesses both
male and female reproductive organs during its lifetime. But by close
observation, I learned that the male and female organs mature at
different times (so-called dichogamy). In this species, the flower
is characterized by the development of male organs (maturation of
stamens/ pollen), shown in the upper photo, before the
appearance of the corresponding female organs ( stigma), shown in
the flower of the bottom photo. This phenomenon is referred to as
protandry. Click here to see more about this.
* Rishon LeZiyyon, 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 21 weeks, 6 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.


Spring and Summer Figs

July 23, 2020

Menashe_fig1

Menashe_fig2

Photographer: Menashe Davidson
Summary Author: Menashe Davidson

Ficus carica is an Asian species of flowering plant in
the mulberry family, known as the common fig (or just the fig).
The fig tree, a deciduous tree, has long been an integral part of
the landscape and agriculture of the eastern Mediterranean region
-- a staple food for humans for thousands of years. What is
commonly accepted as a fruit is a hollow fleshy inflorescence
stalk inside which tiny flowers develop, known as the syconium. The
flowers aren’t visible outside the syconium because they bloom inside
the infructescence.

During a walk on May 8, 2020, in a herbaceous area near Ayalon

Related EPODs

Spring and Summer Figs Blossoming of Tajinastes Baboon’s
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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 1 week, 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.


Archive - Expansion Cracks

August 23, 2020

Expansionbreak copy

Each Sunday we present a notable item from our archives. This EPOD was
originally published August 23, 2003.

Provided by: Kent Barnes
Summary authors & editors: Jim Foster; Kent Barnes

Why is this sidewalk buckled? All materials expand and contract with
daily and seasonal temperature variations. Solid rock, or manmade
substances such as concrete, or even steel, can generate huge internal
forces when there isn't enough room to expand. The photo above was
taken on a hot (near 100 F or 37.4 C) summer day (July 13, 2003) in
Great Falls, Montana, and the concrete sidewalk rafted as a result of
the high temperatures. However, even though expansion cracks are
evident, they weren't sufficient to handle the pressures of the
constrained concrete.


Related EPODs

Archive - Expansion Cracks Encore - Snell's Window
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Applied Sciences Links

* BBC: World Water Crisis
* Indoor Air Quality
* Mathematics in Nature
* A Mathematical Nature Walk
* NASA: Applied Earth Sciences
* Remote Sensing Tutorial

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

https://epod.usra.edu

--- up 5 weeks, 3 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.


Great Beauty in Dark Days

October 23, 2020

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Photographer: Menashe Davidson
Summary Authors: Menashe Davidson

"No occupation is so delightful to me as the culture of the earth, and
no culture comparable to that of the garden." - Thomas Jefferson

Gardening, besides being a practical, life-nurturing task, is to me
also always a spiritual activity. I’m fortunate in that I’m able to
maintain a commercial bearing citrus plantation and a home
garden in which ornamentals, vegetables, herbs, are
grown in pots. The photo above, taken on July 30, 2020, in my
home garden in Rishon LeZion, Israel, demonstrates how I add
interest and beauty by mixing flowers with different characteristics.
Flower-packed groups using four different species allows me to obtain
the look I desire.

Ruellia (top left) - a popular perennial ornamental plant, flowers
from midspring through the first cool days of fall, with purple/blue
flowers.
Lily (top center) - herbaceous flowering plant growing from bulbs,
with large prominent flowers, flowering late spring to midsummer.
Hollyhock (top right) - an annual/biennial prominent plant with
very impressive flowers from May through July on stalks that can reach
heights of 9 ft (3 m).
Zinnia (bottom) - most popular to grow in summer months. An annual
plant, grown from seeds, flowering from May to October.
* Rishon LeZion, 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 8 weeks, 3 days, 20 hours, 20 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (21:1/186)