Transcript userfiles/1208/my files/properties of weatherx?id=484010

• Weather is the daily conditions of the atmosphere.
• Weather forms in the lowest layer of the atmosphere,
the troposphere.
• To describe weather, scientists study 4 properties:
1. air temperature
2. humidity
3. air pressure
4. wind
• Air temperature- caused by the amount of
direct sunlight that is heating the Earth’s surface
• More sunlight = higher, warmer temperatures.
• Humidity- the amount of water vapor in the air
• More water vapor = higher humidity = the air
feels more damp and sticky
Thermometers are used to measure the
air temperature of an area.
Two temperature measurement systems:
Fahrenheit and Celsius.
System
Boiling Point
Freezing Point
Fahrenheit
Customary
212°
32°
Celsius
Metric
100°
0°
A hygrometer is used to measure humidity, or the amount of
water vapor in the air. Hygrometers can be analog or digital.
• Air has weight and it pushes onto the Earth’s surface.
• Air pressure- the force put on an area by the weight of the air
above it
• The particles of cool air are closer together. Cool air is heavier
and has higher air pressure.
• The particles of warm air are spread farther apart. Warm air
weighs less and has lower air pressure.
In other words,
cool air
and warm air
A barometer is used to measure air
pressure. Air pressure is also called
atmospheric pressure.
• Air in motion is called wind.
• Wind is caused by the uneven heating of the
Earth’s surface.
• Different parts of the Earth’s surface absorb
different amounts of the sun’s energy, so the
temperatures are different.
• Air moves from high pressure places (cool air
places) to low pressure place (warm air
places).
WIND
During the day, the land heats up faster. The water is
cooler than the land, so the wind blows towards the
land. At night, the land cools off pretty quick. The land is
cooler than the water, so the wind changes direction.
An anemometer measures wind speed. The
wind is caught in the cup-looking devices
and it begins spinning.
A weather vane, or wind vane, tells you
which way the wind is blowing. Think
opposites: if the vane is pointing east, the
wind must be coming from the opposite
direction, or
the west.
Rain gauges collect
precipitation as it
falls. A rain gauge
can be made with
many different
materials. For
example, any clear
container with
measurement
markings on the
outside would work as a rain gauge.