Download Weather and Climate Revision Notes

Weather and Climate Revision Notes
Weather- The day-to-day state of the atmosphere, can be taken at
any given moment.
Climate- The pattern of weather recorded over a long period of time
(usually 30 years).
Weather Instruments and Elements:
Factors Affecting Climate:
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Latitude- the further north or south of the equator, the colder it
becomes.
Altitude- temperature decreases with height (the rate of
decrease is known as the lapse rate- the temperature will drop
0.6˚ for every 100m climbed).
Distance from sea- the sea heats up and cools down slowly so it
heats up land around it in winter and cools down land around it
in summer.
Wind Direction- Northerly winds bring colder temperatures and
southerly winds bring warm temperatures (northern hemisphere).
Ocean Currents- Different ocean currents bring different
conditions
Aspect- In the northern hemisphere south facing slopes receive
more sunlight
The rain shadow effect- The west coast of a country receives
more rain than the east.
Air masses- Air masses move around and the direction they are
coming from affects the weather they bring.
Air Masses:
Distance
from sea:
Weather Symbols:
Weather Systems:
Depressions (Low Pressure System)
Characteristics:
 Isobars close together as winds are strong.
 Winds blow anti-clockwise.
 Moves from west to east.
 Summer and Winter brings rain wind and cloud.
 UNSTABLE WEATHER CONDITIONS.
Depressions form over the ocean when warm light air and cold heavier air
meet (the masses DO NOT MIX). The warm air rises above the cold air to
produce a front. The rising air cools and condenses as it rises to form rain.
1- Warm Front: Prolonged rain, temperatures fall, thick low clouds, increased
wind speed (gusts) and pressure continues to fall
2- Warm Sector: Pressure steadies, mild temperature, clouds thin with steady
wind and drizzles of rain.
3- Cold Front: Pressure rises and there is a sudden drop in temperature, clouds
thicken and wind speed increases (sometimes gale force), very heavy rain
(possibly thunder/sleet/hail)
4- Cold Sector: Pressure continues
to rise, temperature remains cold,
clouds thin and winds speeds drop
with showers giving way to dry spells.
Troughs of low pressure‘V’ shaped troughs bring heavy rain
and pressure is lowest towards middle
of the ‘V.’ (appear in groups).
Occluded fronts occur when the cold
front catches up with the warm front
causing all the warm air to be forced up rapidly,
this results in short periods of very heavy rain.
Anticyclone (High Pressure System)
Characteristics:
 Isobars well spaced as there are only light winds.
 Winds blow clockwise.
 Summer- warm, sunny with little or no cloud
and light winds. Winter- Clear, calm, sunny
conditions but cold and frosty nights with possible fog and mist.
 STABLE WEATHER CONDITIONS.
Ridge of high Pressure- ‘V’ shape with highest pressure in middle which brings
short settled spells between 2 periods of rainy weather.
Isobars connect areas of equal air pressure
Forecasting the Weather
Weather stations
-All elements are recorded here many times a day.
-Automatic weather stations are used in area where
few people live (e.g the desert) and records
information on air pressure, temperature, wind and
humidity.
Radiosonde balloons- Are sent into the air carrying weather instruments
and send back information by radio.
Satellites- Orbit the earth and take pictures of clouds and pressure
systems.
Radar- Is used to find out the direction and how fast snow/hail/rain is
moving
Aircraft- Carry weather instruments and record data
Weather Ships- Record all information on all weather elements in the
seas and oceans, this information is very important for
people who work at sea. It can also be used to predict
future weather for land areas