Geysers
Geysers are a spectacular
demonstration of the power of the Earth under our feet. Geysers are hot
springs which, by a build up of pressure, erupt periodically and shoot
water into the air. Geysers occur worldwide but over half of the world’s
geysers occur in Yellowstone National Park. Yellowstone hosts the world’s tallest geyser, Steamboat,
which shoots water up to 90m into the air. Geysers can, like most
natural phenomena, be somewhat unpredictable and this has proved deadly
when people wishing to see an eruption get too close in a fit of
impatience. For a
guaranteed geyser eruption Old Faithful in
Yellowstone probably offers the best bet for tourists in America.
Strokkur on Iceland erupts far more often than Old Faithful and can
rival that geyser for height in major eruptions though.
Fire Whirls
Tornadoes are terrifying events,
but add fire and they become spectacularly terrifying. Fire whirls occur
when the heat from a fire drive the air above it in such a way as to
form a vortex with the cooler air outside. If this vortex acquires a
vertical spin then a fire whirl, a vortex sucking flames upwards, will
form. Fire whirls can be incredibly dangerous as they may pick up burning
debris and so spread the flames. When Tokyo was struck by an earthquake
in 1923 an enormous fire whirl was created by the massive numbers of burning wooden buildings. The whirl was a major factor in the burning to death of 38,000 people. Smaller whirls are commonly seen at the front of fires in grasslands.
Light Pillars
In very cold weather, when ice
crystals are suspended in the atmosphere, light pillars may form in the
sky. The light pillars form around natural light sources, like the
setting sun or moon, but can also be created by man-made light. The ice
crystals serve to reflect light back at us and, as we cannot see the
crystals, trick us into believing there is a pillar of light in the sky.
The higher the ice crystals, the taller the light pillar will appear.
Maelstroms
Maelstroms, hugely powerful
whirlpools, have a long history in fiction as being terrible dangers to
sailors. In real life there have never been any cases of large ships
being sunk by maelstroms. The swirling masses of water in maelstroms,
usually driven by unusually strong tides, are impressive. The
Corryvreckan on the west coast of Scotland can be heard miles away as
huge waves up to fifteen feet
high crash back into the sea. Huge whirlpools have always attracted
adventurous souls and the Corryvreckan was first swum by George Orwell’s
one-legged brother-in-law. Maelstroms can be found world wide and
chartering boats to them has become a popular tourist activity.
Sand Storms
Sand storms are spectacular to
look at but devastating to be in. Dust or sand storms have always
bedeviled desert travelers who may become lost in them or even smothered
by the sand they deposit. Sand storms occur when a strong wind whips up
soil and sand particles into the atmosphere and carry them away. Sand
storms can be so large that they are visible from space. Each year forty
million tons of dust are carried from the Sahara to the Amazon basin.
The carrying away of top soil can destroy agriculture or deposit
necessary minerals. A wall of dust billowing out of the desert is one of
the great images of the power of nature.
Solar Eclipses
The Earth is special in that we
have a moon which, at times of eclipse, will perfectly cover the disc of
the Sun. This happens because the Sun’s diameter is approximately 400
times larger than that of the Moon, but the Sun is also 400 times
further away from it. During a total solar eclipse the corona, a plasma
layer around the Sun, becomes visible. Eclipses have fascinated mankind
since the dawn of time, but have been understood and predicted for
thousands of years. Now, with the ability to travel the globe, there are
tourists who will travel to wherever the next total eclipse will occur.
Aurora
In my opinion there is no greater
natural spectacle than the Aurorae. I first saw them while standing on a
frozen lake in the north of Finland. We had left our little fire hut on
the shore because a very faint green glow could be seen over the
treetops. As we watched, a wall of green swept silently across the sky,
flecked with pink lines. When you see a picture of the
aurorae you do not get the sense of motion or scale. The aurorae occur
when particles, ejected on the solar wind, are channeled by the Earth’s
electromagnetic field into the atmosphere. As the particles strike the
atmosphere they ionize atoms which then release light. Some people
report hearing a crackling sound when aurorae are particularly intense,
but this has never been confirmed.
Monarch Butterfly Migration
The Monarch butterfly (Danaus
plexippus) provides one of the most beautiful of all animal displays.
Individually they are a pretty orange and black, but when they mass for
migration they fill the air with color. The migration path of the
butterflies covers a large part of North America.
The migration is prompted by the fragility of the butterflies to cold
and so, as winter approaches, they head south. In these warmer areas the
butterflies overwinter in large groups that may cover whole trees. No
one individual will survive the whole migratory route due to the
butterflies’ ephemeral nature. Their descendants will, however, continue
to put on this beautiful migratory display.
No comments:
Post a Comment