Download The Restless Atmosphere - Scoil Mhuire Geography

Weather...
You can’t see me, but you feel me, you can’t touch
me, but I can touch you. I have been called the
“Breathe of the Gods”, or the killer and giver of
life, gentle and fierce, friendly and enemy, angry
and happy. The Native Americans called me
Moriah, and Snow Eater (Chinook). The Japanese
call me Kaze and in Russia I am called Veter. I can
shatter homes, or wake a child from a peaceful
sleep or bring relief in times of need. I can spread
the most dreaded diseases or bring a welcome
freshness. What am I?
Weather is....

The current state of the
atmosphere...what is happening right
now
The Earth’s Atmosphere
Main points to remember as we
learn about weather:
The sun warms the earth’s surface and
therefore all the air above the surface
 The earth is warmed most at the equator and
least at the poles---why?
 The air above land is warmed more quickly
than air above water.
 Warm air expands and rises, creating an area
of low pressure; cold air is heavy and sinks,
creating an area of high pressure

High Pressure and Low
Pressure
Winds and Air Pressure
Remember…
• Rising air and descending air produce
different kinds of weather
Depressions
•
A Depression is an
area of Low
Atmospheric Pressure.
•
Depressions are also
known as Cyclones.
•
Depression often pass
over Ireland.
•
Depressions bring wet
and windy weather.
This is why we receive
lots of rain.
Anticyclones
•
An anticyclone is an
area of high pressure.
•
Anticyclones bring
clear sunny weather.
•
There are few clouds
and a gentle breeze.
Fronts
•
When two air masses meet they do not mix very well because of their
different temperature, pressure and humidity.
•
Where the two air masses meet is called a Front.
•
We will look at two types of Fronts, a Cold Front and a Warm Front.
Fronts: the boundary between 2
air masses

Warm Front: warm air slides over
departing cold air- large bands of
precipitation form
This is
the
symbol
on a
map for
a warm
front
Cold Fronts

This is the symbol
for a cold front
Cold air pushes under a warm air mass.
Warm air rises quickly=narrow bands of
violent storms form
Occluded Front

This is the
weather map
symbol for an
occluded front
2 air masses merge and force warm air
between them to rise quickly. Strong
winds and heavy precipitation will occur
Reading a weather map

ISOBAR= connects areas of equal
pressure BAR comes from BARometric
pressure
Reading a weather map...

Isotherm: Connects areas of equal
temperature; therm means temperature
Understanding the weather
• Rte player – weather
• Weather charts
The water cycle
Water: a renewable resource
The Water Cycle Keywords
1.
2.
3.
4.
5.
Evaporation
Condensation
Cloud
Percipitation
Run Off
Water
• Water is a basic natural resource needed
to maintain human and animal life and to
grow food
• It is a renewable resource
The Water Cycle
Run Off
Important terms
• 1. Evaporation – Water
transferring from the ground into
water vapour in the air.
• 2. Condensation – Water
vapour in the air turning back
into a liquid.
• 3. Cloud – Water droplets are
held in the air in the form of
clouds.
• 4. Precipitation – Water that
falls to the ground in the form of
Hail, Rain, Sleet, or Snow.
• 5. Run – off – Water running
over the ground back to the sea.
Activity
• Draw and explain the water cycle into your
copies.
• Water cycle song
• http://www.youtube.com/watch?v=o3BVa7
PH_JE&feature=youtube_gdata_player
Water Cycle
song
Clouds
•
Clouds are made when water vapour condenses into tiny droplets.
•
There are many different types of clouds.
•
The most common types of clouds are;
1.
2.
3.
Cirrus Clouds
Cumulus Clouds
Stratus Clouds
TYPES OF CLOUDS

Cirrus Clouds: wispy, feathery clouds
Form only at high levels,
therefore are made of ice
crystals
Types of Clouds

Cumulus Clouds: are puffy white cotton
ball looking clouds
Cumulonimbus Clouds

These are thunderstorm clouds
Types of Clouds

Stratus Clouds: clouds that form in flat
layers- cover all or most of the sky and
are low level clouds
Rainfall
•
Precipitation means hail, rain, sleet or snow.
•
Rain is the most common type of precipitation.
•
Rain occurs when warm air is forced to rise. As the warm air rises it
cools. Cold air cannot hold as much water vapour as warm air, so
condensation occurs. Clouds are formed and rain occurs.
•
There are 3 different types of rain, because there are 3 different reasons
why warm air is forced to rise.
1.
2.
3.
Relief rainfall
Frontal (cyclonic) rainfall
Convectional rainfall
Relief Rainfall
•
Relief rainfall occurs when;
- Warm moist air moves in from the sea.
- It hits a mountain range at the coast and is forced to rise.
- It cools as it rises.
- Condensation occurs, clouds form and it starts to rain.
Frontal Rainfall
•
Frontal rainfall occurs when;
– Warm and cold air masses meet at a Front
– The warm air mass moves up over the cold air mass.
– The warm air cools and condensation takes place.
– Stratus clouds form and rain occurs.
Convectional Rainfall
•
Convectional rain occurs when;
– The sun shines on the land and heats up the air above it.
– The heated air rises quickly.
– As it rises it cools and condensation occurs.
– Cumulus clouds are formed and heavy rain occurs.
The Weather
•
When we talk about the weather we usually talk about the
following things.
1.
2.
3.
4.
5.
6.
7.
Temperature
Precipitation (rain etc)
Sunshine
Wind speed
Wind direction
Atmospheric pressure
Humidity
All of these different aspects of the weather can be measured.
There are different weather instruments to measure each thing.
These instruments are usually in a weather station.
Temperature
•
Temperature is
measured using a
Thermometer.
•
It is measured in
degrees Celsius (°C).
•
Lines on a weather
map showing areas of
equal temperature are
called Isotherms.
Temperature
•
You need to know how to calculate the;
1. Mean Temperature
2. Temperature Range
Mean Temperature: Add all the monthly temperatures, then divide by 12.
Temperature Range: Take the lowest temperature away from the highest temperature.
Mon
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sept
Oct
Nov
Dec
Mean
Monthly
Temp
10
13
15
17
18
21
23
28
21
15
12
11
Precipitation
• Precipitation is
measured using a Rain
Gauge.
• It is measured in
millimetres.
• Lines on a map
showing areas of equal
precipitation are called
Isohyets.
Sunshine
• Sunshine is measured
using a Campbell
Stokes sunshine
recorder.
• Sunshine is measured
in Hours per day.
• Lines on a weather map
showing areas of equal
sunshine are called
Isohels.
Wind
• We can measure 3 things about the wind.
• Wind Speed – Using an Anemometer.
• Wind Direction – Using a Wind Vane.
• Wind Strength – Using the Beaufort Scale
The Beaufort Scale
• The Beaufort Scale
describes the effect
the wind has on the
landscape.
• Wind strength is
divided into 12 forces.
• The Beaufort Scale
was invented by an
Irishman.
Atmospheric Pressure
• Atmospheric pressure is
measured using a
Barometer.
• It is measured in
millibars.
• Lines on a weather map
showing areas of equal
pressure are called
Isobars.
A Barograph can also be used to measure atmospheric pressure
• What is Humidity?
Humidity is the amount of moisture in
the air. It can be measured in various
ways, but the most usual is to
describe it as 'relative' humidity. This
is expressed as a percentage. A
relative humidity of 100% means the
moisture content of the air is the
maximum possible at any particular
temperature. The hotter the air, the
more moisture it can hold.
Humidity
• Humidity is measured
using a Hygrometer.
• A common type of
hygrometer is a wet and
dry bulb thermometer.
• It is expressed as a %.
100% is the maximum.
What you have learnt
1. Weather associated with high and low
pressure.
2. Fronts
3. Reading weather charts
4. Water cycle
5. Rainfall
6. Measuring weather