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a. Define the term “atmospheric pressure” & describe the movement of
air currents between areas of high & low pressure
Atmospheric pressure: is the force per unit area due to the weight of the
atmosphere (a layer of gases).
 These gases are kept in place by the force of gravity. measured in
hectoPascals.
 Air moves from high air pressure to low air pressure. (breeze or wind)
 Typically, the air pressure varies from about 980 hPa to 1100 hPa- normal
is 1006 hPa
b. identify the distance between isobars on a weather map indicates the
relative change in atmospheric pressure in an area.
 If the isobars are close together, this means that places that are not far apart
experience a large difference in air pressure. As a result, the winds in this
region will be strong.
 If the isobars are a long way away from each other, this means that the
difference in air pressure between two places is not very large. As a result,
the winds will be quite gentle.
c. describe the relative pressures involved in the formation of tropical
cyclones & tornadoes
 Cyclones & tornadoes are examples of extremely violent storms produced
by large differences in air pressure. They are also known as typhoons or
hurricanes, depending on where you live.
 The factors they have in common are:
o They are formed when an area experiences extremely low air
pressure
o They are produced by extreme difference in air pressure
o They often form over water & then move on to land
 The differences include:
o Cyclones are longer in duration, have slower winds & are slower
moving
o Tornadoes are shorter in duration, have faster winds & are faster
moving
d. describe technological advances that contributed to increased
understanding of meteorology
 Meteorology is the study of the weather & climate. There are several major
aspects to it:
o Measuring the characteristics of the weather
o Predicting the weather
o Researching ways to improve the measurement methods
 To predict the weather, meteorologists need to measure quantities like air
pressure, humidity, temperature & wind speed & direction.
 They are measured in as many places as possible, as often as possible,
normally a person is needed to make any measurement. These
measurements then have to be interpreted to make predictions about the
weather.
 The basic tools for measuring these characteristics include:
e. describe the relationship between the monitoring of
weather patterns by radar & laser light & the analysis of
reflected wave patterns by computers
Radar
 Use microwaves
 Waves reflect off clouds of rain
 The time taken for the pulse to return tells the operator how
far the clouds are away
 The shapes of the waves tell us what they are showing
o Longer wavelengths used to show water (liquid)
o Shorter wavelengths show vapour (gas)
 Experienced operators can tell rain from hail & snow
Doppler Radar
 Slightly different
 Used to measure the speed of air
 If wind is coming towards you it’s a different colour on the
screen to wind moving away from you
 It works the same way in which a police radar
 The faster object is moving towards you the high frequency
of the reflected wave
Lidar (laser Light)
 Light detection & ranging
 Measures distance
 Measures speed
 Measures rotation
 Measures chemical composition & concentration
 Used to study atmosphere including pollutant & gas
concentration
f. explain why satellite photographs of cloud patterns have
improved the reliability of interpretations of weather
regularities & knowledge of global weather patterns
 Help to trace the life cycle of weather systems,
 better data about air pressure, cloud patterns & solar
radiation estimates
 A new Japanese-built satellite, MTSAT-1R, has started
snapping hourly photographs of weather fronts in the AsiaPacific region & is beaming them down to a base station at
Cribb Point, near Hastings in Victoria.
VIS Images
 Visual images
 Photographs from satellites
 Show cloud coverage
IR Images
 Infared images
 Used to find out about temp of oceans & the atmosphere
Radar Network
 Radio waves are sent form a radio dish
 Waves travel away from the dish & if they hit water or ice
they are reflected back
 Computers measure the time they take to return & calculate
the distance to them
 Computers then display the data on a colour coded map