Weather Journal
Mount Desert Island, Maine
Spring, 2014
Sarah Duff
Climate and Weather
Professor: Sarah Hall
June 6th, 2014
1 Table of Contents
Cloud Types
1. Cumulus
2. Cumulus humilis
3. Cumulus congestus
4. Formation of cumulonimbus
5. Cumulus fractus
6. Stratocumulus
7. Altocumulus
8. Altocumulus undulatus
9. Cirrus
10. Cirrus fibratus
11. Cirrocumulus
12. Cirrostratus
13. Cirrostratus fibratus
14. Stratus
15. Stratocumulus
16. Stratus Nebulosus
17. Stratus Translucidus
18. Altostratus
19. Nimbostratus
20. Contrails
21. Fall streaks
Freezing Precipitation
30. Snow
31. Ice
32. Icicles
Atmospheric Optics
33. Sun- Solar radiation
34. Moon- Reflection
35. Shadows
36. Sunset
37. High pressure system
38. Blue mountains
39. Rainbow
40. 22- Degree Halo
41. Cloud iridescence
42. Crepuscular rays
43. Cloud silver lining
Fog
44. Advection fog
45. Valley fog
Evidence of Paleoclimate Events
46. Roche moutonnée
47. Glacial striations
48. Crescentic fractures
49. Echo Lake
Precipitation
22. Rain
23. Drizzle
24. Dew
25. Virga
26. Adhesion/surface tension
27. Condensation
28. Evaporation
29. Conduction
Long Exposure/ Series Photographs
50. Strong wind
51. Tides
2 Cloud Types
1.
Cumulus Clouds
Phenomena: Cumulus clouds over the ocean
Date: April 17th, 2014
Time: 11:00 AM
Location: College of the Atlantic Campus, Bar Harbor, Maine
View of Photo: East
Cumulus clouds are low-laying clouds, which means that they form below 6,600ft
in the atmosphere, and are generally made up of water droplets, except during
snowstorms, when they can be made up of ice crystals. It is a general rule that each.
Cumulus clouds are usually lumpy with flat bottoms. This is because clouds condense
when the temperatures reach the dewpoint, which is directly related to altitude. Cumulus
clouds can be taller than that are wide, or wider than they are tall, as seen above. It’s a
general rule that a cumulus cloud will be about the size of an observer’s fist (from the
observer’s point of view) when it is held up to the sky for comparison.
(Ahrens, 1994)
3 2.
Cumulus Humilis
Phenomena: Cumulus humilis clouds over the bay
Date:
Time:
Location:
View of Photo: Southeast
Cumulus humilis clouds are a variety of cumulus clouds that appear in individual
puffs about the size of an observer’s fist (from the observer’s point of view) when it is held
up to the sky for comparison. They usually have flat bottoms, and are wider than they are
tall. They have limited vertical growth. Cumulus humilis clouds are known as fair-weather
clouds and usually signify clear weather.
(Ahrens, 1994)
4 3.
Cumulus Congestus
Phenomena: Cumulus congestus over the Atlantic
Date: May 8th
Time: 2:00 PM
Location: Standing on the Green, Bar Harbor, Maine
View of Photo: Northeast
Cumulus congestus clouds are a form of cumulus clouds that have significant
vertical growth. They are usually not single cloud puffs like cumulus humilis, but join
together, and cover a significant amount of the sky. They can appear with clear weather,
or develop into a cumulonimbus cloud and bring heavy precipitation. Sometimes the tops
of the clouds resemble the heads of cauliflowers.
(Ahrens, 1994)
5 4.
Formation of a Cumulonimbus
Phenomena: Cumulus congestus clouds that formed into cumulonimbus clouds
Date: May 26th, 2014
Time: 5:00 PM
Location: College of the Atlantic campus
View of Photo: Northwest
This photo shows the development of cumulus congestus clouds, which passed over
Bar Harbor and grew into a cumulonimbus cloud further north. Cumulonimbus clouds are
enormous storm clouds that produce heavy rain and often thunder and lightning. They
have extensive vertical growth, and if viewed from far away, an anvil top can be
sometimes be seen spreading out from the top of the cloud. Cumulonimbus stretch from
low to high altitudes- where the water vapor turns into ice crystals in the freezing
temperatures. From directly underneath a cumulonimbus, the anvil top cannot be seen,
but they can be identified extensive cloud cover, heavy rain and sometimes lightning and
hale.
(Ahrens, 1994) (Pretor-Pinney, 2011)
6 5.
Cumulus Fractus
Phenomena: Observing cumulus fractus clouds from Cadillac Mountain
Date: May 7th
Time: 6:22 PM
Location: The top of Cadillac Mountain, looking towards Bar Harbor
View of Photo: North
Cumulus fractus clouds are a form of cumulus clouds that are sheared from larger
cumulus clouds by wind, and so have ragged edges. The best examples of these in this
photo are near the top of the frame, though the larger clouds towards the middle of the
frame are breaking up as well.
(Ahrens, 1994)
7 6.
Altocumulus
Phenomena: Altocumulus clouds
Date: May 3rd, 2014
Time: 6:331 PM
Location: College of the Atlantic campus
View of Photo: West
Altocumulus clouds are mid-level clouds, typically ranging between 6,500 and
20,000 ft. They are formed by groups of cloudlets that can vary greatly in appearance, but
generally small fluffy mounds. They resemble cirrocumulus clouds slightly, except that
they are lower in the sky and so appear larger. They are also made of water vapor instead
of ice crystals, and cirrocumulus does not exhibit the dark and lights shading that
altocumulus do. Altocumulus cloudlets are shaded on the side away from the sun.
(Ahrens, 1994) (Pretor-Pinney, 201
8 7.
Altocumulus Undulatus
Phenomena: Altocumulus undulatus clouds
Date: May 8th, 2014
Time: 9:21 AM
Location: College of the Atlantic campus
View of Photo: North
Altocumulus undulatus clouds are a variety of altocumulus clouds that display
cloudlets in a wave-like pattern. The ripple or wave-like patterns are a result of wind sheer,
and align in the direction of the wind at their altitude. These clouds can resemble
cirrocumulus clouds, but the cloudlets appear larger than cirrocumulus (because they are
lower in the atmosphere). Although altocumulus clouds do not produce precipitation, they
can a sign of precipitation in the next 24 hours, or simply an overcast day.
(Ahrens, 1994) (Pretor-Pinney, 2011)
9 8.
Cirrus Clouds Over the Ocean.
Phenomena: Cirrus clouds over the ocean
Date: April 19th, 2014
Time: 12:35 PM
Location: College of the Atlantic campus, Bar Harbor, Maine
View of Photo: East
Cirrus clouds are high-level clouds, which means that they form above 20,000ft in
the atmosphere. Because the temperature is so cold at their elevation, cirrus clouds are
almost always made up entirely of ice crystals. The semi-transparent trailing wisps
following the thicker lines of cloud are sometimes called “mare’s tails”. Cirrus clouds are
associated with fair weather, and are sometimes called “fair weather clouds.”
(Ahrens, 1994)
10 9.
Cirrus Fibratus
Phenomena: Cirrus fibratus clouds
Date: May 29th, 2014
Time: 7:38 PM
Location: College of the Atlantic campus
View of Photo: West
Cirrus fibratus clouds are a type of cirrus clouds with filaments of wispy clouds.
Sometimes, like in this picture, the wisps (called mare’s tails) are attached to larger puffs of
clouds. Other times, they only appear as streaks of clouds. These strands are high-level
clouds and are so usually made up of ice crystals.
(Ahrens, 1994)
11 10. Cirrostratus
Phenomena: Cirrostratus clouds around the sun
Date: May 26, 2014
Time: 12:58 PM
Location: Forest Street, Bar Harbor, Maine
View of Photo: Overhead
Cirrostratus clouds are high-level clouds that are made up of ice crystals. They
usually cover a significant portion of the sky in what appears to be an unbroken sheet.
Cirrostratus clouds are prone to producing coronas and halos around the sun, because of
the light refracted off of the ice crystals. A better photo of a halo can be found later on in
this journal. The black line on the left side of the photo is a telephone wire.
(Ahrens, 1994)
12 11. Cirrostratus Fibratus
Phenomena: cirrostratus fibratus clouds around the sun
Date: May 13th, 2014
Time: 3:23 PM
Location: College of the Atlantic campus
View of Photo: Overhead
Cirrostratus fibratus are a variety of cirrostratus clouds that appear filamentous.
These are high-level clouds that are made up of ice crystals, and are prone to creating
atmospheric optics. A photo can be found later on in this journal showing cloud
iridescence around the sun. The light refracting through the ice crystals in this filamentous
cloud cause the colors to appear.
(Ahrens, 1994)
13 12. Cirrocumulus
Phenomena: Cirrocumulus clouds
Date: May 27th
Time: 1:48 PM
Location: College of the Atlantic Campus
View of Photo: Southeast
Cirrocumulus clouds are high-level clouds usually made up entirely of ice crystals.
The are comprised of many cloudlets, and appear very small to an observer on Earth,
because they are so high in the atmosphere (about six miles up). These clouds resemble
altocumulus clouds, but can be distinguished from them by their size. If an observer holds
his, her, or their finger up to the sky, cirrocumulus cloudlets will appear smaller than the
width of a finger.
(Pretor-Pinney, 2011)
14 13. Stratus
Phenomena: Stratus clouds
Date: June 4th, 2014
Time: 9:53 AM
Location: Forest Street, Bar Harbor, Maine
View of Photo: Northwest
Stratus clouds are low-laying clouds that usually have a base below 2000m. They
are the lowest forming of all cloud types. They are grayish-white shapeless masses that
usually block out much of the sun, and linger for hours- sometimes producing light
drizzle. Because they have such low-laying bases, they sometimes cover the tops of
mountains or tall buildings, and emit a sense of gloom.
(Ahrens, 1994) (Pretor-Pinney, 2011)
15 14. Stratocumulus
Phenomena: Stratocumulus clouds with the sun setting behind them.
Date: May 5th, 2014
Time: 7:47 PM
Location: The top of Cadillac Mountain
View of Photo: West
Stratocumulus clouds cover large areas of the sky with thick puffy mounds that
sometimes produce light precipitation. In this photo, the sun can be seen setting behind
the clouds. Only some light and color appears to pass through because the clouds are so
thick. Stratocumulus clouds are low-altitude clouds that range between 1,000 and 4,500 ft.
(Pretor-Pinney, 2011)
16 15. Stratus Nebulosus Clouds
Phenomena: Stratus nebulosus clouds over and obscuring the tops of mountains
Date: April 7th
Time: 5:30 PM
Location: Kebo golf course, Bar Harbor, Maine.
View of Photo: Southwest
These low-laying stratus clouds usually form below 6,500ft. Seen here, the bottom
layer of the clouds are brushing the tops of mountains, showing that their base is quite
near to the ground. Stratus clouds are hazy, horizontally layered clouds that range in color
from white to grey and sometimes produce light precipitation. Stratus nebulosus are a
variety of stratus clouds are grey and featureless, and the most common form of stratus
clouds. Patches of snow can also be observed
(Pretor-Pinney, 2011)
17 16. Stratus Translucidus
Phenomena: The sun partially obscured by a layer of stratus translucidus clouds
Date: May 10th
Time: 7:02 PM
Location: Forest Street, Bar Harbor, Maine.
View of Photo: West
Stratus translucidus are a variety of stratus clouds that are thin enough to show the
outline of the sun or moon. They are very low-laying, widespread layer of cloud that
sometimes produce a light drizzle. Their bases are generally no higher than 1,500 ft off the
ground. The sun can be seen in this photo, partially obscured by a layer of stratus
translucidus clouds. The sunlight is being diffused by the layer of clouds, and so appears
hazy.
(Pretor-Pinney, 2011)
18 17. Altostratus
Phenomena: Altostratus clouds obscuring the sun, cumulus clouds and a seagull
Date: April 27th, 2014
Time: 4:21 PM
Location: Cottage Street, Bar Harbor, Maine
View of Photo: West
Altostratus clouds are mid-level, featureless clouds that range between 6,500-16,000ft
in the atmosphere. It’s an overcast layer of clouds that stretch on for miles. Often,
altostratus clouds are formed from the thickening of cirrostratus clouds, and can develop
into nimbostratus clouds. Cumulus clouds can also be seen in this photo, towards the
bottom of the frame and across the middle-left hand side.
(Pretor-Pinney, 2011)
19 18. Nimbostratus
Phenomena: Nimbostratus clouds
Date: May 17, 2014
Time: 4:40 PM
Location: Forest Street, Bar Harbor, Maine
View of Photo: Southeast
Nimbostratus clouds are one of two forms of clouds that often produce rain. The
other form is the cumulonimbus cloud, and cumulonimbus clouds are easy to discern
because they appear with heavy rain and usually thunder and lightning. Nimbostratus
clouds are less conspicuous. They creep in and lay low to the ground, and can remain for
days. These clouds remained over Bar Harbor for an entire weekend, from May 167h to the
19th, occasionally producing a light drizzle, and giving the area a melancholy,
claustrophobic feeling. Nimbostratus clouds often proceed a warm fronts, because of the
rising, warm air.
(Pretor-Pinney, 2011)
20 19. Contrails
Phenomena: Contrails left by plains flying over COA campus.
Date: May 14th, 2014
Time: 5:30 PM
Location: College of the Atlantic campus, Bar Harbor, Maine
View of Photo: Southwest
Plains leave contrails when the hot engines heat up the air and water molecules
that pass through the turbines or come near enough to them to be heated, and causes trails
of clouds to appear behind them. When many contrails are seen in the sky, it could be
thought that there were a lot of plains overhead that day: this is a misconception however.
Generally, there is the same number of plains in the sky every day. The number of
contrails that are seen depends on how long they remain in the sky. Sometimes plains
hardly leave a mark behind them, and sometimes the trails can stretch across the sky. If
the contrails remain in the sky for a long time, multiple trails can be viewed togethergiving the sky a striped appearance. Contrails remain longer in the sky on days when
there is high humidity.
(Ahrens, 1994)
21 20. Fall Streaks
Phenomena: Fall streaks from cirrus clouds
Date: May 13th
Time: 2:23 PM
Location: College of the Atlantic campus
View of Photo: East
Fall streaks are the result of ice crystals precipitating from high-altitude clouds. The
falling crystals evaporate before they reach the ground, and the result is wisps of white
filaments in the sky originating from a larger, more opaque cloud.
(Ahrens, 1994)
22 Precipitation
21. Rain
Phenomena: Raindrops falling, splashing and creating a puddle.
Date: April 26
Time: 4:18 PM
Location: College of the Atlantic campus, Bar Harbor, Maine.
View of Photo: Northwest
Condensation occurs when temperatures cool and drop below the dew point and
the air becomes %100 saturated. For water to condense, there first needs to be a
condensation nuclei. When condensation occurs in the air to create clouds, these
condensation nuclei are dust or salt particles in the air. But condensation alone does not
produce precipitation and not all clouds produce rain. For precipitation to occur, the
droplets that clouds are composed of need to be large and heavy enough to fall from the
cloud. Even the smallest updraft is enough to keep tiny cloud droplets in the air, and even
if they do fall, they may evaporate before falling far. This is where the collision and
coalescence process comes into play. As droplets are carried throughout the cloud by
updrafts, they bump into other cloud droplets and can merge into larger droplets. In tall
cumulonimbus clouds, for example, the droplets are carried high into the atmosphere, and
have the opportunity to merge with many other cloud droplets until a water droplet is
large and heavy enough to fall from the cloud as a raindrop. This is why cumulonimbus
clouds usually produce large raindrops (Ahrens, 1994).
23 21. Drizzle
Phenomena: Drizzle from nimbostratus clouds
Date: May 17th
Time: 4:36 PM
Location: Kebo golf course
View of Photo: West
Drizzle is a form of rain where the water droplets are smaller than 0.5mm in
diameter. These water droplets are falling from nimbostratus clouds, which hung over Bar
Harbor for three days, occasionally producing drizzle. Drizzle can also fall from other
forms of stratus clouds, such as stratocumulus clouds. Condensation falls from clouds
when the temperature drops below the dew point. These clouds usually indicate a stable
atmosphere- meaning that cold air is above warm air.
(Ahrens, 1994)
24 22. Dew
Phenomena: Dew on the grass and a dandelion
Date: May 21st
Time: 10:24 AM
Location: College of the Atlantic campus
View of Photo: North
Dew forms on grass and objects near the ground on mornings after there were low
temperatures at night. Cold nights are often caused in part by cloudless skies, because
infrared waves given off by the ground are not impeded by insolating cloud cover. In the
early morning, solar radiation warms the ground and the air directly above it, causing it to
rise and condenses, and leave tiny water droplets on grass blades and other conducting
surfaces like these. This photo was taken in late morning, but the dew remained on the
ground because a shadow from a building had blocked the sun’s rays until a few minutes
before I walked across the grass (and got my feet wet).
(Ahrens, 1994)
25 23. Virga
Phenomena: Virga falling from a stratocumulus cloud.
Date: May 7th
Time: 6:50 PM
Location: The top of Cadillac Mountain, Bar Harbor, Maine
View of Photo: West
Virga is the term for when rain or snow falls from a cloud but evaporates before
reaching the ground. This photo was taken from the top of Cadillac Mountain just after
the sun set. The orange colors in the sky make the blue of the falling water droplets easy
to see: the falling streaks thin as they descend, and do not all the way to the ground.
Changes in temperature throughout the atmosphere explain why the water turns from
liquid back to vapor as it falls.
(Ahrens, 1994)
26 24. Adhesion/Surface Tension
Phenomena: Water droplets clinging to flowering shadbush
Date:
Time:
Location: The woods above Kebo Golf course, Bar Harbor, Maine
View of Photo: N/A
Adhesion is when dissimilar molecules or surfaces to cling to each other. In this
case, water droplets from a light drizzle are clinging to a flowering shadbush. The
occurrence of adhesion is also needed for the water droplets to form in the sky. Water
droplets cannot forms unless there is a particle of dust or salt in the air for the first water
molecules to adhere to. In this sense, this photo of water droplets clinging to flowers is
representative of how those water droplets were first formed high in the atmosphere before
falling to Earth.
(Ahrens, 1994)
27 25. Condensation on a Window
Phenomena: Condensation left on a bathroom window after a hot shower
Date: May 18th, 2014
Time: 12:20 PM
Location: Bathroom of photographer’s home, Bar Harbor, Maine
View of Photo: Southeast
Condensation is the process of water vapor becoming a liquid: but water vapor
cannot condense unless it has a something to condense on. When clouds form, the water
vapor condenses on particles in the air, such as dust or salt. Fog forms on bathroom
mirrors and windows when you take a hot shower, because the water vapor in the air is
coming into contact with the cold, flat surface of the window or mirror. Similar effects
happen when you leave a glass of ice water outside on a warm day and the glass seems to
“sweat.” The same thing happens to people who wear glasses when they come inside after
being outdoors on a cold day. In this photo, the word “Condensation” is written in the
condensed water on the window. When warm air comes in contact with a cold surface,
the air cools, and cannot “hold” as much water. Water then condenses on surfaces such as
this windowpane.
(Ahrens, 1994)
28 26. Evaporation
Phenomena: Evaporation from the sidewalk
Date: June 4th
Time: 2:09 PM
Location: College of the Atlantic campus
View of Photo: South
Evaporation is the process of liquid water transforming into water vapor. On this
day, rain blew under the overhang above the red bricks at College of the Atlantic campus.
After it stopped raining, the water on areas of the bricks that were exposed to the rays
from the sun evaporated. The bricks under the overhang in this photo are still wet, because
they are shaded from the sun, so the water is evaporating at a slower rate.
(Ahrens, 1994)
29 27. Conduction
Phenomena: Conduction as shown by a pot of water being heated by a stove
Date: May17th, 2014
Time: 9:45 PM
Location: Photographer’s kitchen
View of Photo: N/A
Thermal conduction is when heat is transferred from one molecule to another. In
this case, the heat from the stovetop burner is heating the pan, which is heating the water
inside and causing it to change from a liquid to a vapor. Thermal conduction also occurs
outside, and contributes to weather. For instance, during the day, the ground is warmed
by solar radiation from the sun. During the night, the ground cools off by releasing
infrared radiation. In the morning, the process starts again: the sun heats the ground, and
the air nearest to the ground is then heated, which causes it to rise and expand.
(Ahrens, 1994)
30 Freezing Temperatures
28. Snow
Phenomena: Snow on the ground
Date: April 16th, 2014
Time: 10:14 AM
Location: College of the Atlantic
View of Photo: Southeast
Snowflakes, like rain, require condensation nuclei to be present in the air for the
first water molecules to freeze to (particles like salt or dust in the air). Snowflakes can take
many shapes from prisms to needles to complex lace-like structures called dendrites. Their
shape depends upon the environment and temperatures in which they form. The longer
snowflakes are carried up and down through the cloud, the more opportunity the collision
and coalescence process has to act, and the more complex the shapes become. The photo
above shows snow that fell the night before, in a late snowstorm- April 16th.
(Ahrens, 1994).
31 29.Ice
Phenomena: Ice on a small pond
Date: April 7th, 2014
Time: 5:01 PM
Location: Kebo gold course, Bar Harbor, Maine
View of Photo: Southwest
In a controlled environment, water changes from liquid to ice at 0 degrees Celsius.
Outside, the freeing point of water is also determined by other factors, such as what
minerals are in the water, and how much direct sunlight the water is exposed to. Salt is
poured on the roads to melt ice, because salty water has a lower freezing point than pure
H2O. Air bubbles that are trapped in the ice cause the white coloration that is often seen
in ice, such as in the photo above. One way for scientists to study paleoclimate is by
taking core samples of ice from Earth’s Poles or on mountaintops in order to look at the
gasses trapped in those air bubbles. By looking at the composition of CO2, methane, and
nitrous oxide at different levels in the ice, we can chart how our atmosphere has changed
over millions of years.
(Ahrens, 1994)
32 30.Icicles
Phenomena: Icicles on a stone wall
Date: April 23
Time: 1:28 PM
Location: College of the Atlantic Campus, Bar Harbor, Maine
View of Photo: South
After a late cold snap on April 23rd, Bar Harbor experienced snowfall and ice
formation. This was a late snowfall, because Maine receives more hours of sunlight as the
seasons change into spring and the temperatures warm. These small icicles were found in
the afternoon after a night of precipitation. Icicles form when solar radiation melts ice or
snow, and causes the liquid water to drip off a surface. If the air temperature is below
freezing, the water will refreeze as it drops. New drips may also flow down the icicle and
refreeze, which creates icicles made up of many frozen water droplets- as seen in the
photograph.
(Ahrens, 1994)
33 Atmospheric optics
31. Sun
Phenomena: The sun with cumulus fractus clouds below it.
Date: April 9th
Time: 10:54 AM
Location: College of the Atlantic campus
View of Photo: Overhead
The Sun supplies the Earth with heat and light. It is the driving force behind
evaporation, wind. Earth’s trajectory around and position relative to the sun determines
the climates, temperatures and seasons on earth. Without it, life on Earth would be very
different if not impossible. The sun is a burning star that emits radiation on a spectrum
between ultraviolet, visible light, infrared and infrared. It travels to the earth in the form
of electromagnetic waves.
(Ahrens, 1994)
34 32.The Moon
Phenomena: The crescent moon
Date: May 5th, 2014
Time: 7:47 PM
Location: The moon viewed from the top of Cadillac Mountain.
View of Photo: Overhead
The moon is an example of reflection of light. The portion of the moon that we can see
in this photo is reflecting light from the sun. Earth casts a shadow on the moon when it is
in between the sun and moon, which makes some parts appear dark, and creates the
waxing a and waning effect. Reflection is an important part of the energy system of
Earth: albedo is when sunlight is reflected from the earth by reflective surfaces such as
snow. The moon is also important to weather on earth, because the moon’s relativity to
earth determines the strength of the tides. The closer and larger the moon, the more
drastic the tides are. More information on tides can be found later in this journal.
(Ahrens, 1994)
35 33.Shadows
Phenomena: Shadows on a hillside cast by trees
Date: May 3rd, 2014
Time: 6:47 PM
Location: The forest behind forest street, Bar Harbor, Maine
View of Photo: Southeast
Shadows are cast on the ground when the sun is at an angle to an object. Visible
light is blocked by the object- such as trees, as seen here- and a shadow appears on the
other side of it. The lower the sun is in the sky, the more extreme angle the light is, and
the longer the shadow will be.
(Ahrens, 1994)
36 27. Sunset
Phenomena: a colorful sunset viewed from the top of Cadillac Mountain
Date: May 8th, 2014
Time: 6:45 PM
Location: The top of Cadillac Mountain, Bar Harbor, Maine
View of Photo: West
The sun rises and sets from our perspectives on Earth, because of Earth’s rotation
around the sun. The sun sets and rises at different times depending on the observer’s
longitude and latitude and also the time of year. The tilt of the earth is the force behind
the timing of the sunset and sunrise, and also the seasons observed on Earth. People living
near Earth’s equator receive 12 hours of daylight and 12 hours of night each day. The
beautiful colors that are sometimes seen in the sky as the sun sets are due to particles in
the atmosphere that scattering the sunlight. This photograph also demonstrates virga,
which is precipitation seen falling from the clouds and evaporating before it reaches the
ground.
(Ahrens, 1994)
37 28. Clear Blue Sky
Phenomena: Rayliegh scattering
Date: April 17th
Time: 1:00 PM
Location: Sand Beach, Mount Desert Island, Maine
View of Photo: East
The sky appears blue to our eyes because of an optical phenomenon known as
Rayliegh scattering. Light from the sun is a combination of all colors of the rainbow (red,
orange, yellow, green, blue, indigo and violet) and also colors that we can’t normally see,
such as ultraviolet and infrared. Light is scattered by molecules and particles in the air, and
different wavelengths appear to us as different colors. Clouds appear white because the
molecules in clouds are larger than the wavelengths of light that are passing through them,
and so scatter all colors (Mie scattering). Our eyes see that combined combination of
colors as white. When there are few or no clouds in the sky that is an indication of a highpressure system. We see the sky as blue because shorter wavelengths scattered more
strongly, and blue is one of the shortest wavelengths. The sky fades to lighter blue, and
almost white near the horizon because the observer is looking through more of Earth’s
atmosphere from that angle.
(Ahrens, 1994) (Gibbs, 1997)
38 29. Blue mountains
Phenomena: Blue mountains in the far distance during a sunset
Date: May 9th, 2014
Time: 7:05 PM
Location: The top of Cadillac Mountain, Bar Harbor, Maine
View of Photo: West
Some mountains in the distance appear blue because of a phenomenon called
Rayliegh scattering (to learn more about Raylight Scattering read the above journal
entry). Light is scattered by particles in the atmosphere, and the Wavelength that appears
as blue to us is scattered the most frequently. The further away an object is, the more of
the atmosphere the observer is looking through, and the paler and bluer the object will
appear.
(Ahrens, 1994) (Gibbs, 1997)
39 30. Rainbow
Phenomena: A rainbow
above Bar Island
Date: May 20th, 2014
Time: 7:08 PM
Location: College of the
Atlantic dock, looking
out towards Bar Island
View of Photo: East,
with the sun behind the
photographer
Rainbows are an atmospheric phenomenon caused by the refraction of light within
water molecules in the atmosphere. Light from the sun appears white to our eyes, but in
reality, it is the combination of wavelengths that when separated appear to us as red,
orange, yellow, green, blue, indigo and violet. It’s also made up of wavelengths that we
can’t normally see, such as ultraviolet and infrared. When an observer has the sun to his,
her or their back, and there is precipitation in front of him, her or them, a rainbow can
sometimes be observed. The observer must also be no higher than 42 degrees above the
horizon. When white light is shone through a prism, it splits into red, orange, yellow,
green, blue, indigo and violet. When a rainbow is seen, the same phenomenon is
occurring within each water molecule. The light passes through the front of the drop, and
is reflected of the back- each wavelength at a different angle. Rainbows are seen about ten
times each year. This photo is only a partial rainbow, but they can stretch up and form an
enormous arch in the sky. Occasionally a double rainbow can be spotted.
(Pretor-Pinney, 2011).
40 31. 22- Degree Halo Around the Sun
Phenomena: A 22-degree halo around the sun
Date: May 26th, 2014
Time: 12:58 PM
Location: Forest Street, Bar Harbor, Maine
View of Photo: Overhead
Halos are found in cirrostratus, cirrus, and cirrocumulus clouds, and can be seen
around either the sun or a full moon. These clouds are high-level clouds, and so are made
up of ice crystals. When the crystals in the upper atmosphere in front of the sun or moon
take the shape of hexagonal columns these halos may be spotted. Light from the sun or
moon is refracted through the crystals at a 22-degree angle, and sometimes halos are
referred to as 22-degree halos. They are usually only spotted around a full moon, because a
waxing or waning moon doesn’t reflect enough light to produce the effect.
(Ahrens, 1994) (Pretor-Pinney, 2011)
41 32. Cloud Iridescence
Phenomena: Cloud iridescence around the sun in cumulus fractus clouds
Date: April 9th, 2014
Time: 11:36 AM
Location: College of the Atlantic campus
View of Photo: Overhead
Small water droplets that are diffracted by the sun’s light can occasionally produce
iridescence in clouds. Diffraction is when light bends around the edge of an object. The
objects that the light is bending around are the water droplets in the cumulus clouds in the
photograph above. Diffraction of light can also cause coronas around the sun (when water
droplets or ice crystals are larger) and the silver linings around some clouds. See those
journal entries for more information.
(Ahrens, 1994) (Pretor-Pinney, 2011)
42 33. Crepuscular rays
⇐ Phenomena: Crepuscular rays radiating from the setting sun behind cumulus clouds.
Date: May 16th
Time: 6:59 PM
Location: Forest Street
View of Photo: West
Crepuscular rays are sunrays that can shine through holes in stratocumulus clouds, or
from behind cumulus clouds (as seen above). Crepuscular rays are seen when sunlight is
scattered in the sky by water particles in the air that are not abundant enough to appear as
clouds. Shadows from the clouds block parts of the sunlight, which gives the multiple-ray
effect. The arrow indicates the location of the crepuscular rays. The black lines in the
photo are telephone wires.
(Pretor-Pinney, 2011)
43 34. Cloud Silver Lining
Phenomena: Cloud silver linings and crepuscular rays
Date: May 26th, 2014
Time: 5:15 PM
Location: College of the Atlantic campus
View of Photo: West
There’s a saying that goes: “Every cloud has a silver lining” but in actuality, not
every cloud does. This optical phenomenon is caused by sunlight being diffracted by large
water droplets around the edges of some clouds. Diffraction is when light bends around
the edge of an object- the object in this case being the edge of a cumulus congestus cloud.
Crepuscular rays can also be seen in this photograph.
(Ahrens, 1994) (Pretor-Pinney, 2011)
44 Fog
Valley fog
Phenomena: Valley fog on Champlain Mountain
Date: May 13th, 2014
Time: 11:25 AM
Location: Near the top of Champlain Mountain, Bar Harbor, Maine
View of Photo: North
Valley fog is a result of cold, humid air sinking and gathering in low places, such as
valleys. This photo might be an example of fog sinking down into the valley between two
mountains. On this day, stratus clouds were overhead. We hiked up through a patch of
low-laying fog between the mountains, and then broke through to clear air. When stratus
clouds form at ground level, it is called mist or fog.
(Pretor-Pinney, 2011)
45 35. Advection Fog
Phenomena: An arch of advection fog (Below) and a boat and Bar Island through the fog
(Above)
Date: May 14th, 2014
Time: 9:00 AM
Location: College of the Atlantic
View of Photo: North
Advection fog often appears
in early mornings. It is a result of
warm air blowing over a colder
surface- causing it to condense. In
this case, the fog appeared when the
warm air that was heated from the
rising sun moved from land to over
the cold ocean water. In the photo on
the left: an arch of fog can be seen
over the ocean. In the photo above:
Bar Island and the Osprey can be seen
through the fog. This fog might also
be referred to as a Mist. Fog is
technically defined as mist that has
less than 1 kilometer of visibility,
meaning that one cannot see through
it past a distance of 1 Kilometer. Mist
has a visibility of more than 1-2
kilometers. (Pretor-Pinney, 2011)
46 Evidence of Paleoclimate events
27. Sheep Porcupine Island: Roche Moutonnée
→
Phenomena: Roche moutonnée as demonstrated by Sheep Porcupine Island
Date: June 4th, 20014
Time: 10:13 AM
Location: Standing on the Green, Bar Harbor, Maine
View of Photo: North
Roche moutonnées are a result of glacial activity on a landscape. The direction of
the arrow over the photo indicates the direction that the glacier moved. The glacier moved
from North to South and exerted extreme pressure on the rocks: causing scouring and
creating the shallow slope that can be clearly observed here. The right side of the island is a
much steeper slope, and is much rockier as a result of glacial plucking (the depositing of
rocks and boulders). Glacier deposits and scouring created all of the Porcupine Islands
around 18,000 years ago.
(Gilman, 1988)
47 28. Echo Lake- Glacial Topography
Phenomena: Echo Lake- Topography caused by glaciation
Date: May 30th, 2014
Time: 10:01 AM
Location: The cliffs overlooking Echo Lake
View of Photo: Northeast, Southeast
Glacial activity on Mount Desert Island around 18,000 years ago caused the Ushaped valley where Echo Lake now resides. The photo on the left is looking out towards
the Northeast, where the glacier moved southwards, most likely following the path of an
already established river. The photo on the right is looking out towards the Southeast,
where Echo Lake ends and a bog and forest now reside. The glacier that first created the
valley reached past where the forest is now before retreating. The valley then filled with
water, creating the lake, which has been filling back in with sediments slowly over time.
Moraines can be found in the forest at the glacier’s furthest reach, where the glacier
retreated and reformed again over many years. Till and different soil types are therefore
found in bands across the valley.
(Gilman, 1988).
48 29. Glacial Striations
↑ ↑ ↑ Phenomena: Glacial striations in rock
Date: May 30th, 2014
Time: 8:45 AM
Location: Somesville Boat launch, Bar Harbor, Maine
View of Photo: South
Glaciers moving across the landscape on Mount Desert Island 18,000 years ago
caused glacial striations on rocks that can be clearly observed in some areas. The
undersides of glaciers scouring the ground as they moved southwards caused the lines in
the rocks in this photo. The striations in the rocks are therefore all North-South facing (as
the overlaying arrows demonstrate. This photo was taken at the Somesville boat launch,
which is a particularly good place to view glacial striations. I left my foot in the frame for
size-comparison. The distances between the striations are very small.
(Gilman, 1988).
49 30. Crescentic Fractures
Phenomena: Crescentic fractures left by glacial activity
Date: May 30th, 2014
Time: 8:54 AM
Location: Somesville Boat launch, Bar Harbor, Maine
View of Photo: Crescentic fractures are pointing south
Crescentic fractures are horseshoe-shaped gouges in rocks left by glacier activity.
In this photo, I left my feet in the frame for size-comparison. The gauges were left in the
rocks by glaciers that were retreating and refreezing on Mount Desert Island around
18,000 years ago. These types of glacier marks were left by boulders that were trapped by
the ice at the bottom of the ice sheet. The gauges are deeper at the point of the
(Gilman, 1988).
50 Long Exposure/ Series Photos
27. Strong Wind
Phenomena: Strong wind blowing tree branches at twilight
Date: April 10th, 2014
Time: 8:04 PM
Location: Forest Street, Bar Harbor, Maine
View of Photo: East
Wind is caused by air flowing from high pressure to low pressure. Because of the
rotation of the earth and its relation to the sun, the Equator receives the most solar
heating, and the poles receive the least amount of solar heating. The uneven heating of
earth’s surface causes global wind patterns. Smaller, local wind patterns are due to many
factors. Changes in temperature and pressure influence wind strength and direction, as
well as incoming and outgoing storms and the topography in the area. This image was
captured with a camera on a tripod and a slow shutter speed to capture the motion of the
swaying branches. The white streaks in the background are paper birch trees. The moon
can be seen in the background, with a slight corona around it.
(Ahrens, 1994) (Pretor-Pinney, 2011)
51 28. Tides
11:23 AM 2:08 PM Phenomena: Bar Harbor’s bar covered and uncovered by the ocean at different tidal levels
Date: June 4th
Time: 11:23 AM, 2:08 PM
Location: College of the Atlantic, looking out towards Bar Island
View of Photo: Southeast
Tides are predominantly caused by the forces of gravity exerted on earth by the
moon, and by the earth’s tilt. Topography and the gravitational forces of the sun also
affect how large the tides are. The gulf of Maine has some of the largest tides in the world.
Twice a day, there is a high tide and a low tide, and the sandbar connecting Bar Island and
Bar Harbor is low enough in the water that it is covered and uncovered with each high and
low tide.
(Ahrens, 1994)
52 Works Cited
Ahrens, C. Donald. Meteorology Today: An Introduction to Weather, Climate, and the
Environment. Minneapolis/St. Paul: West Pub., 1994. Print.
Gibbs, Philip. "Why Is the Sky Blue?" Why Is the Sky Blue? N.p., May 1997. Web. 07 June
2014.
Gilman, Richard A. The Geology of Mount Desert Island: A Visitor's Guide to the Geology
of Acadia National Park. Augusta, ME: Maine Geological Survey, Dept. of
Conservation, 1988. Print.
Pretor-Pinney, Gavin. The Cloud Collector's Handbook. San Francisco, CA: Chronicle,
2011. Print.