ATMOSPHERE & WEATHER

 

THE AIR

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AIR TEMPERATURE

 

o       Air temperature is measured using a thermometer: a tube with liquid inside

 

§        When the air around the liquid gets warmer; the liquid gets warmer and expands

§        measured by degrees Celsius or Fahrenheit.

§        Scientists use the Celsius scale.

 

SUNLIGHT & AIR TEMPERATURE

 

o       When sunlight warms the solids and liquids on earth, those solids and liquids warm the air above them.

 

o       The further away from Earth the colder it is.

o       Direct sunlight, at noon on a summer day will cause the highest temperature

o       Early morning sun in the winter will not cause the temperature to rise very much.

o       Length of the day will also affect the temperature of the air

**When the day is longer it can warm the solids and liquids on Earth to a higher temperature.

 

AIR PRESSURE

 

§        Air is matter and has mass.

§        The pressing down of the air is called air pressure.

§        Air pressure on the Earth changes:

o       Low-pressure area : a place where warm air rises and pushes down on the Earth’s surface with less pressure.

 

o       High-pressure area:  a place where cool air sinks and pushes down on the Earth’s surface with more pressure.

 

§        Air pressure can be measured using a tool called a barometer.

 

1.    One type of barometer is an upside-down tube filled with mercury. As the air pressure gets higher it causes the mercury to rise in the tube.

 

2.    Another type of barometer has a circular dial in a sealed box. The outside of the box moves lightly as the air pressure changes.  This causes the pointer on the dial to move.

 

WIND - measure its speed and direction

 

A. When the air moves from an area of high pressure to an area of low pressure it causes wind.

 

B. Wind direction is measured using weather tools:

 

1. Wind vane:  rotates on tope of a pole the tail of the vane is pushed by the wind and an arrow on the opposite end of the vane points into the wind. 

 

2. Wind sock: tool that shows wind direction. It can also indicate how strong the wind is blowing.

 

3. Anemometer:  measures the exact speed of the wind.  An anemometer has three or four cups attached to the top of a pole.  The wind causes this part of the anemometer to spin. The number of turns per minute tells the wind speed.