What is weather?
the state of the atmosphere at a particular time.
What is the zone of weather called?
the troposphere.
How is precipitation measured?
a rain gauge.
How is a rain gauge set up?
- part buried in the ground
- on grass (no hard surface)
- no trees/roofs around
- upright
What is air temperature and what is it measured in?
the degree of warmth in the air.
celsius.
What measures the warmest and coldest temperatures of the day?
a maximum-minimum thermometer.
What is humidity?
the amount of water vapour in a given volume of air.
What is the dew point?
when the air is saturated.
What is the equation for relative humidity?
(amount of water vapour in the air/maximum amount of water vapour the air can hold at that temperature) x 100
What is the relative humidity of saturated air?
100%
How is humidity measured?
wet and dry bulb thermometers
hygrometer
How is the wet bulb different from the dry bulb?
- has fine muslin cloth wrapped around it with a container of water underneath it that has a wick of cloth that leads to the muslin so the bulb is always moist.
What happens to the pressure as the altitude increases?
gets lower because there is less air.
Which isolines on a map show pressure?
isobars.
How do you measure pressure?
mercury barometer
aneroid barometer
barograph
What are the site requirements to measure pressure?
kept away from strong air movements
direct sunlight
How is wind velocity measured?
an anemometer.
What scale is used to classify wind destructiveness?
the Beaufort scale.
What instrument shows wind direction?
a wind vane.
What is the prevailing wind?
the most frequently occuring wind in an area.
What are the site requirements for anemometers and wind vanes?
- at least 10m above the ground
- in an open space
- at least 3x the height of the nearest obstacle
What are the different isolines for?
isohyets - lines joining places with the same rainfall
isotherms - lines joining places with the same temperatures
isobars - lines joing places with the same pressure
What is the Stevenson screen?
- houses maximum-minimum thermometers
- wooden box
- can also contain barometer
- door opens away from the sun
- slatted sides allow free-flow of air
- painted white to reflect sun
- sited on grass
What are clouds?
tiny water dorplets or ice particles that are too light to fall to earth.
