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Atmosphere, Weather and Climate
Structure of Earth’s Atmosphere Atmosphere
A layer of air which surrounds the Earth It is held in place by the pull of Earth’s gravitional forces Earth’s gravity is strongest nearer to the surface, therefore, most
of the atmosphere is found near the surface. Consists mostly of:
Nitrogen Oxygen Water vapour Dust particles
The Atmosphere The Atmosphere (cont’d)(cont’d)
Other gases (carbon dioxide, water vapour)
1%
Oxygen 21%
Nitrogen 78%
Upper part of the atmosphere contains little atmospheric water vapour and other gases and experiences no changes in weather.
Troposphere contains most atmospheric water vapour, other gases and dust and experiences weather changes
Importance of the AtmosphereImportance of the Atmosphere
Helps sustain life Protects the Earth
Weather and Weather and
ClimateClimate
WeatherThe Sun’s rays
heat up theEarth’s land and sea surfaces
Heat reflected from these surfaces warm up the air above
Hot air rises and causes condition of the atmosphere to change
Weather VS Climate
Weather and Climate Weather and Climate (cont’d)(cont’d)
WeatherWhen this happens, we experience a change
in weatherMeteorologists define ‘weather’ as the condition
of the atmosphere at a particular place over a short period of time
Weather and Climate Weather and Climate (cont’d)(cont’d)
ClimateWeather pattern of a place over a long period of time,
usually 30 years The basic elements of weather and climate:
SunshineTemperatureHumidityCloudsRainfallAir pressureWind
How Weather and Climate Affect How Weather and Climate Affect PeoplePeople
Weather affects our daily life Climate affects how people live generally
Where people choose to liveTypes of houses people live in
Climate affects food and water supply
Measuring Temperature
Daily Maximum and MinimumDaily Maximum and Minimum
TemperaturesTemperatures
Daily maximum temperature: the highest temperature reading for the day
Daily minimum temperature: the lowest temperature reading for the day
Maximum and Minimum ThermometersMaximum and Minimum Thermometers
Maximum temperature is measured by the maximum thermometer It consists of a glass tube containing mercury and
a metal index When temperature rises, the mercury expands and pushes the metal index
upwards When temperature falls and the mercury contracts,
the metal index stays in place The minimum thermometer works in the same
way, but contains alcohol instead of mercury
Where to Place ThermometersWhere to Place Thermometers
Instruments used to measure temperature are usually placed in a Stevenson ScreenA raised white wooden box with louvres
Shelters the instruments from the direct heat of the SunAllows air to flow freely through itAvoids heat radiating from the ground
Mean Daily TemperatureMean Daily Temperature
The average temperature of a place on any one day Daily recording of this temperature reveals a
pattern which provides a more accurate picture of the climate of the place
Mean Daily Temperature Mean Daily Temperature (cont’d)(cont’d)
Formula for calculating mean daily temperature
Mean
daily
temperature
Daily maximum temperature
+
Daily minimum temperature
2
=
Mean Daily Temperature Mean Daily Temperature (cont’d)(cont’d)
Mean daily temperature for SingaporeDaily maximum temperature is often 32 degrees
CelsiusDaily minimum temperature is often 25 degrees CelsiusMean daily temperature =
=
(32 + 25)OC
2
28.5OC
Diurnal Temperature RangeDiurnal Temperature Range Shows how extreme temperatures can get within a
day Used for describing the climate of a place Formula:
Diurnal
Temperature
range
=
Daily
maximum
temperature
Daily
minimum
temperature-
Diurnal Temperature Range Diurnal Temperature Range (cont’d)(cont’d)
Diurnal temperature range for Singapore= (32 - 25)OC
= 7OC