-Weather is the state of the atmosphere, including temperature,
atmospheric pressure, wind, humidity, precipitation, and cloud cover. It
differs from climate, which is all weather conditions for a particular location
averaged over about 30 years.
There are many different types of weather conditions. The five main types of
weather are: sunny, cloudy, windy, rainy, and stormy.
-2Measuring
the elements of the weather
Weather affects us in many ways. It affects what we do and what we wear, how we
travel and even our moods.
Meteorologists measure weather conditions in different places and use this
information to report and make forecasts about future weather conditions.
This is useful because people can be warned about hazardous weather conditions such
as storms and floods
1-Temperature is measured in Celsius (°C) using a digital thermometer. The
thermometers can be placed in a Stevenson Screen to make sure that the
temperature is taken in a shady environment.
2-Precipitation is measured using a rain gauge. The rain gauge is usually anchored
in the ground with the top of the gauge around 30cm above the ground surface to
ensure that rain splash does not affect the results. The depth of the rain in millimetres
can be read from the side of the container.
3-Wind direction is reported by the direction it is blowing from, according to the
compass. Wind blowing from the west is travelling eastwards so is called a westerly
wind, not an easterly wind. Wind direction is often observed using a wind vane.
4-Wind speed can be measured using an anemometer. The anemometer should be
held at arm’s length, above the head so that the cups can rotate without any
interference. The strength of the wind is measured in knots.
5-Atmospheric pressure is the weight of air pressing down on us. Air is light but
because there is so much of it above us, it exerts a pressure on us. Atmospheric
pressure is measured by a barometer. The units used are millibars.
Differences between Climate vs. Weather
Ice Ages
What is an ice age?
An ice age is a period in Earth's history when the ice on the polar caps
significantly expanded due to an overall lowering of the Earth's global
temperatures. During these periods land in North America and Northern
Europe were covered by giant ice fields and glaciers.
How do scientists know about ice ages?
Scientists have figured out when past ice ages likely occurred by studying the
geology of the land. There are many geological features in Northern Europe
and North America that can only be explained by the movements of
giant glaciers. Scientists also study the chemicals in rocks and fossil
evidence to determine when ice ages have occurred.
Are we living in an ice age?
Yes, you may be surprised to know that we are currently living in an ice age
called the Quaternary ice age. The Earth is in a warmer stage of the ice age
called an interglacial period.
Glacial and Interglacial Periods
There are periods within ice ages that scientists define as glacial and
interglacial.
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Glacial - A glacial period is a cold period when the glaciers are
expanding.
Interglacial - An interglacial period is a warm period where the glaciers
may be receding.
Five Major Ice Ages
Over the course of millions of years, scientists believe that the Earth has
experienced at least five major ice ages.
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Huronian - The Huronian ice age was one of the longest ice ages in the
Earth's history. It lasted from about 2400 to 2100 million years ago.
Scientists think it may have been caused by a lack of volcanic activity
lowering the carbon dioxide in the atmosphere.
Cryogenian - The Cryogenian ice age occurred from 850 to 635 million
years ago. It is possible that ice sheets reached all the way to the
equator. Scientists sometimes call this a "Snowball Earth."
Andean-Saharan - The Andean-Saharan ice age occurred between
460 to 430 million years ago.
Karoo - The Karoo ice age lasted around 100 million years between
360 to 260 million years ago. It is named after glacial tills in Karoo,
South Africa that scientists think were developed during this ice age.
Quaternary - The most recent ice age is the Quaternary ice age. By
scientific definition, we are currently in an interglacial stage of this ice
age. It started around 2.5 million years ago and is still going.
What can cause an ice age?
The Earth is constantly undergoing changes. These changes can impact the
global climate. Some of the changes that can influence an ice age include:
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Earth's orbit - Changes in the Earth's orbit (called Milankovitch cycles)
can cause the Earth to be closer to the Sun (warmer) or further from
the sun (colder). Ice ages can occur when we are further from the Sun.
Sun - The amount of energy output by the Sun also changes. Low
cycles of energy output can help in producing an ice age.
Atmosphere - Low levels of greenhouse gases such as carbon dioxide
can cause the Earth to cool leading to an ice age.
Ocean currents - Ocean currents can have a great impact on the
Earth's climate. Changes in currents can cause ice sheets to build up.
Volcanoes - Volcanic activity can introduce huge amounts of carbon
dioxide into the atmosphere. The lack of volcanoes can cause an ice
age. Increased volcanic activity can put an end to an ice age as well.
Interesting Facts about Ice Ages
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The current interglacial period that the Earth is in is called the
Holocene period.
Most of Canada was covered with ice just 20,000 years ago.
An ice age can occur if the global temperature drops just a few degrees
for a long period of time.
Ice and snow can reflect the Sun's rays and energy, further lowering
the temperature and increasing the length of an ice age.
Mammals from the last ice age that are now extinct include the wooly
mammoth and the saber-toothed cat.
The Earth's
Atmosphere
The earth is surrounded by a layer of gases called the atmosphere. The atmosphere is
very important to life on Earth and does many things to help protect life and help life
to survive.
A Big Blanket
The atmosphere protects Earth like a big blanket of insulation. It absorbs the heat
from the Sun and keeps the heat inside the atmosphere helping the Earth to stay warm,
called the Greenhouse Effect. It also keeps the overall temperature of the Earth fairly
steady, especially between night and day. So we don't get too cold at night and too hot
during the day. There is also a portion of the atmosphere called the ozone layer. The
ozone layer helps to protect the earth from the Sun's radiation.
This big blanket also helps to form our weather patterns and climate. The weather
keeps too much hot air from forming in one place and causes storms and rainfall. All
of these things are important to life and the Earth's ecology.
Air
The atmosphere is the air that plants and animals breathe to survive. The atmosphere
is made up of mostly nitrogen (78%) and oxygen (21%). There are lots of other gases
that are part of the atmosphere, but in much smaller amounts. These include argon,
carbon dioxide, neon, helium, hydrogen, and more. Oxygen is needed by animals to
breathe and carbon dioxide is used by plant in photosynthesis.
Layers of Earth's Atmosphere
The Earth's atmosphere is divided up into 5
major layers:
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Exosphere - The last layer and the
thinnest. It goes all the way to 10,000
km above the Earth's surface.
Thermosphere - The thermosphere
is next and the air is very thin here.
Temperatures can get extremely hot
in the thermosphere.
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Mesosphere - The mesosphere
covers the next 50 miles beyond the
stratosphere. This is where most
meteors burn up upon entry. The
coldest place on Earth is at the top of
the mesosphere.
Stratosphere - The stratosphere
extends for the next 32 miles after the
troposphere. Unlike the troposphere
the stratosphere gets its heat by the
Ozone Layer absorbing radiation
from the sun. As a result, it gets
warmer the further away you get from
the Earth. Weather balloons go as
high as the stratosphere.
Troposphere - The troposphere is
the layer next to the ground or
surface of the Earth. It covers around
30,000-50,000 feet high. This is
where we live and even where planes
fly. Around 80% of the mass of the
atmosphere is in the troposphere.
The troposphere is heated by the
surface of the Earth.