Saturday, June 30, 2012

All About Tides and Seiches

I am so busy right now trying to get product made for the upcoming shows that I just have not made exercise a priority. I am going to make myself hike tonight after I leave the museum, so I'll have some updated sand dunes photos for the blog posting tomorrow.

For today's posting, I decided to post information about tides.

Tides are one of the most reliable phenomena in the world. The word "tides" is a generic term used to define the alternating rise and fall in sea level with respect to the land, produced by the gravitational attraction of the moon and the sun. Twice each day the ocean waters regularly rise and fall along our shores. Basically, tides are very long waves that move through the oceans in response to the forces exerted by the moon and sun. Tides originate in the oceans and progress toward the coastlines where they appear as the regular rise and fall of the sea surface. When the highest part, or crest of the wave reaches a particular location, high tide occurs; low tide corresponds to the lowest part of the wave, or its trough. The difference in height between the high tide and the low tide is called the tidal range.

A horizontal movement of water often accompanies the rising and falling of the tide. This is called the tidal current. The incoming tide along the coast and into the bays and estuaries is called a flood current; the outgoing tide is called an ebb current. The strongest flood and ebb currents usually occur before or near the time of the high and low tides. The weakest currents occur between the flood and ebb currents and are called slack tides. In the open ocean tidal currents are relatively weak. Near estuary entrances, narrow straits and inlets, the speed of tidal currents can reach up to several kilometers per hour.

Gravity and inertia act in opposition on the Earth’s oceans, creating tidal bulges on opposite sites of the planet. On the “near” side of the Earth (the side facing the moon), the gravitational force of the moon pulls the ocean’s waters toward it, creating one bulge. On the far side of the Earth, inertia dominates, creating a second bulge.

The highest tides on planet Earth occur near Wolfville, in Nova Scotia's Minas Basin Bay of Fundy. The water level at high tide can be as much as 16 metres (52 feet) higher than at low tide.

High tides happen every 12 hours and 25 minutes (or nearly an hour later each day) because of the changing position of the Moon in its orbit around the Earth.

At mid-tide, the flow in  the Bay of Fundy equals the combined flow of all the rivers and streams on Earth!

Here is a video of the tidal changes in the Bay of Fundy.

Lake Superior doesn't have tides like the oceans.  However, periodically the water levels rise and fall by as much as one foot due to a phenomenon called a 'seiche' (SAYSH, a French word that means 'to sway back and forth'). This happens when water piles up on one side of the lake because of wind or high barometric pressure and then shifts back to the other side. Small seiches occur all the time, but sometimes strong ones can cause ships to bang together in harbors, or leave them high and dry for a few minutes.

In Lake Superior, small seiches occur almost continuously. These go largely unnoticed. However, the biggest seiches can bang ships together in harbors, snap their mooring lines, and buckle their plates.
On July 13, 1995, a big Lake Superior seiche left some boats hanging from the docks on their mooring lines when the lake water suddenly retreated. In that seiche, lake water went out and came back within fifteen to twenty minutes at Ashland, Wisconsin, Marquette and Point Iroquois, Michigan, and Rossport, Ontario. People who witnessed it were amazed. In just a few minutes, water levels changed about three feet.

In 1998 a seiche occurred in Two Harbors, Minnesota, that caused several hundred thousand dollars of damage to vessels loading iron ore at the Duluth Missabe Iron Range Railway Company docks. This seiche surged a vessel almost 12 to 15 feet.

Friday, June 29, 2012

Mars Rover Update

Today I decided to post an update about the Mars rovers.

NASA's twin robot geologists, the Mars Exploration Rovers, launched toward Mars on June 10 and July 7, 2003, in search of answers about the history of water on Mars. They landed on Mars January 3 and January 24 PST, 2004 (January 4 and January 25 UTC, 2004).

Primary among the mission's scientific goals have been to search for and characterize a wide range of rocks and soils that hold clues to past water activity on Mars. The spacecraft landed on opposite sides of Mars that appear to have been affected by liquid water in the past.

After the airbag-protected landing the robots settled onto the surface and opened, rolled out to take panoramic images. These images gave scientists the information they needed to select promising geological targets that tell part of the story of water in Mars' past. Then, the rovers drove to those locations to perform on-site scientific investigations.

Initially the expectations were to have the robots function for a matter of months and drive  up to 40 meters (about 44 yards) per day, for a total of up to one 1 kilometer (about three-quarters of a mile). Both goals have been far exceeded! 

Spirit's traverse map Spirit's total odometry is unchanged at 7,730.50 meters (4.80 miles).  More than 1,300 commands were radiated to Spirit as part of the recovery effort in an attempt to elicit a response from the rover. No communication has been received from Spirit since Sol 2210 (March 22, 2010). The project concluded the Spirit recovery efforts on May 25, 2011.

Opportunity's traverse map through Sol 2989
Total odometry as of Sol 2989 (June 20, 2012), is 21.43 miles (34,491.99 meters). 

Opportunity has been exploring the north end of Cape York on the rim of Endeavour Crater.

With Mars Odyssey still working to recover from their safe mode event, Communication with the rover has been limited to just two UHF relay passes per week from Mars Reconnaissance Orbiter. NASA scientists have been successful in controlling this robot and making it still do some driving.

On June 12, 2012, the rover drove a little over 56 feet (17 meters) to the north, approaching the boundary between the Cape York geologic unit and the Meridiani plains. On June 20th Opportunity bumped just over 16 feet (5 meters) north to straddle the contact unit between Cape York and Meridiani, and position a candidate target within the work volume of the robotic arm. Opportunity also performed two atmospheric argon measurements on June 13 and June 18, 2012, using the Alpha Particle X-ray Spectrometer.  The rover continues to benefit from solar array dust cleaning events, which have greatly increased the daily energy production. As of Sol 2989 (June 20, 2012), solar array energy production was 526 watt-hours.

The Mars Exploration Rovers act as robot geologists while they are on the surface of Mars. You can explore the various parts of the rover by clicking on the image below.

In some senses, the rovers´ parts are similar to what any living creature would need to keep it "alive" and able to explore.  The rovers each have:

A body: a structure that protects the rovers´ "vital organ.s"

Brains: computers to process information.

Temperature controls: internal heaters, a layer of insulation, and more.

A "neck and head": a mast for the cameras to give the rovers a human-scale view.

Eyes and other "senses": cameras and instruments that give the rovers information about their environment.

Arm: a way to extend its reach.

Wheels and "legs": parts for mobility.

Energy: batteries and solar panels.

Communications: antennas for "speaking" and "listening."

Rover Facts
  • Cruise vehicle dimensions: 2.65 meters (8.7 feet) diameter, 1.6 meters (5.2 feet) tall Rover dimensions: 1.5 meter (4.9 feet) high by 2.3 meters (7.5 feet) wide by 1.6 meter (5.2 feet) long
  • Weight: 1,062 kilograms (2,341 pounds) total at launch, consisting of 174-kilogram (384- pound) rover, 365-kilogram (805-pound) lander, 198-kilogram (436-pound) backshell and parachute, 90-kilogram (198-pound) heat shield and 183-kilogram (403-pound) cruise stage, plus 52 kilograms (115 pounds) of propellant
  • Power: Solar panel and lithium-ion battery system providing 140 watts on Mars surface
  • Science instruments: Panoramic cameras, miniature thermal emission spectrometer, Mössbauer spectrometer, alpha particle X-ray spectrometer, microscopic imager, rock abrasion tool, magnet arrays
Mission Facts
  • Launch vehicle: Delta II 7925
  • Launch of Spirit: June 10, 2003, from Cape Canaveral Air Force Station, Fla.
  • Launch of Opportunity:  July 7, 2003
  • Earth-Mars distance at launch: 103 million kilometers (64 million miles)
  • Earth-Mars distance on landing day: 170.2 million kilometers (105.7 million miles)
  • One-way speed-of-light time Mars-to-Earth on landing day: 9.46 minutes
  • Total distance traveled Earth to Mars (approximate): 487 million kilometers (303 million miles)
  • Near-surface atmospheric temperature at landing site: -100 C (-148 F) to 0 C (32 F)
  • Primary mission: 90 Mars days, or "sols" (equivalent to 92 Earth days)
  • Cost: Approximately $820 million total, consisting approximately of $645 million spacecraft development and science instruments; $100 million launch; $75 million mission operations and science processing

Here are a series of photos of the mission.  The photo below is the first picture of earth ever taken from another planet.

Here is a picture of Mars.

Some of the Rover photos....

In this photo, the sun is sinking just below the rim of Gusev Crater. It appears about 2/3 the size of the sun as seen from Earth during sunset, since Mars is about 48 million miles farther away from the sun.

Thursday, June 28, 2012

Evening Break Wall Walk

Last night I attempted to have a beach fire east of town with a friend visiting from out of town. We knew that with warm temperatures and a south wind that the potential for stable flies was high. We were correct. The flies were horrible. Instead we headed to Sable Lake and cooked out at the overlook where the stiff south breeze kept the bugs away.

I decided to look on the internet to learn more about these annoying insects.

Here is the information published by the National Park Service about bitint insects in the Pictured Rocks Natonal Lakeshore area.

What's Biting You?
An outdoor adventure at Pictured Rocks National Lakeshore is an exhilarating experience but, at certain times of the year, our visitors can be distracted by the smallest inhabitants of the north woods: the biting flies.

Earliest to appear on the scene in mid-spring are the mosquitoes and black flies. The female mosquito, as with most biting flies, is the one doing the biting. She requires a blood meal in order to get enough protein for her eggs to develop properly. Most male biting flies feed on pollen or nectar from flowers. Male mosquitoes have feathery antennae and live about one week. Mosquitoes lay their eggs in calm or standing water, and the larvae are aquatic. Many diseases are transmitted by mosquitoes, and it is best to avoid their bites as much as possible.

Black fly larvae are also aquatic, but prefer to live in running water like streams or rivers. Black fly larvae attach themselves to rocks in the stream by a suction cup on their tail end, and filter out food particles from the water with their feathery fan-like structures around their mouths. After pupation, the adult black fly rides on a bubble of air to the waters surface and flies out of the water. The adult females are vicious biters, but luckily, North American black flies do not transmit disease to humans. Black fly attacks on people, cattle, horses and pigs tend to be concentrated around the ears and head. In addition to the blood loss, effects of the insect saliva can cause a variety of problems, with swelling and intense skin irritation most common.

In the streams black fly larvae attach themselves to rocks or other submerged materials and feed on organic particles they filter from the passing waters. Trailing vegetation or rotted aquatic plants also are attractive to black flies, providing sites for the larvae to attach for feeding. Breeding may also occur in rivulets formed by the flooding of fields.

The black fly life cycle can be rapid, taking about three weeks from egg laying to maturation of the adult. Only the female bites, the blood meal being used to provide protein for egg maturation. Adults live about two weeks. Populations can grow very rapidly. Two to four generations may be produced annually. Individual females may lay several hundred eggs.

Seldom seen or heard but sometimes felt is the No-See-Um, also called Punkies or Biting Midges. No-See-Ums resemble miniature, short-legged mosquitoes, and are usually less than 3 millimeters long. Only females of a few species bite humans. The majority bite other insects or eat nectar, but they also do bite humans. Their larvae are mostly aquatic and are scavengers or predators. No-See-Ums are less common than other biting flies in Pictured Rocks. At times they can have concentrated large populations, but they usually only last a day or so.

The stable fly is the biting fly at the Pictured Rocks beaches in mid to late summer. It is a relative of the house fly, but it bites. The stable fly is a blood-feeding pest known to attack almost any kind of warm-blooded animal. Its body is grey, with a distinctive checkerboard pattern on the abdomen. It is commonly referred to as the 'beach fly or black fly' and prefers to bite its victim's legs and ankles. Both the male and female stable fly bite, but they also feed on pollen. Unlike the other biting flies, the larvae of the stable fly are terrestrial, and live in and eat decaying vegetation. Stable flies are not known to transmit disease in humans, but are annoying enough to drive people away from beaches when they are numerous. It looks like the common house fly except that its mouthparts are adapted for biting and sucking blood. The stable fly feeds by inserting its proboscis (beak) through the skin and then sucking blood from its host. Females can live up to a month and may require several blood meals during this period in order to continue laying eggs. It is a daytime feeder, with peak biting occurring during the early morning and late afternoon.  

It is always best to play it safe and avoid being bitten by biting flies. Use protective clothing or insect repellant, and carry an allergy medicine or anti-histamine in case of an allergic reaction to a bite.

Here are a few photos I took out on the break wall last night. Unfortunately, clouds obscurred the sunset.

Wednesday, June 27, 2012

Beach Scenes and Changes in Grand Marais

Yesterday morning I conducted an agate rockhounding class for two grandsons of part-time Grand Marais residents. Drew and Evan seemed to enjoy the class.

Another family was enjoying the beach...

The comprehensive refurbishing of the Pickel Barrel is now done.  For those of you who visit Grand Marais, you are probably aware that four years ago another contracter supposedly refurbished the historic structure, but did not do it correctly.  So the Grand Marais Historical Society hired master craftsmen to try to repair and save the structure.  They built a wider top to deflect the rain, replaced rotten wood, and made other repairs.  The next tast will be to repaint the building.

The township has torn down the old fire/ambulance barn.  A few years ago voters turned down a milliage to build a new facility.  However, the township proposed and the voters passed an "operations" milliage that did not clearly state its purpose.  The funds from this tax increase is being used to build a new facility.

A video taken on the beach yesterday....

Tuesday, June 26, 2012

Agates Close Up, Bay Update, and More

I decided to pull out my USB microscope camera and play with a few rocks. Wow. Some of the detail is incredible. In fact I had a hard time narrowing it down so I just included  few extra photos.

This first photo is of one of the eyes in the museum's original mascot agate that was on the back cover of the first agate book, Understanding and Finding Agates.

And how about that Ocean Jasper ...

Here are some close ups of the Lake Superior moss agate that a found a few Mother's Days back...

Does the agate pocket look like Lake Superior?

Here are a couple of other shots of another moss agate ...

The next two shots are of a beach fulgerite.  This fulgerite formed when lightning hit a piece of driftwood on the beach east of Grand Marais.  The energy from the lightning bolt penetrates into the sand below the log and fuses it into instant rock.

Perhaps my favorite in this group are of the chalcedony roses that I picked up in the desert of Arizona this past January.

Drusy quartz with mineral staining...

An update of the bay showing that the break wall is growing.  However, the local TV news announced that the Army Corp of Engineers has halted the second bid to complete the project.  I just tried to find the bid listing on the Army Corp web page.  I did not see it.  Thus, I am not sure what happens to the project since the Army Corps also is withholding their $1.8 million.

Here is a map showing the difference between the original break wall and the location of the new break wall.

Check out these bike helmets.  Brothers Aiden and Jacob are showing them off.