Weather Flashcards
Climate
The weather conditions prevailing in an area in general or over a long period
Weather
The state of the atmosphere at a particular place and time as regards heat, cloudiness, dryness, sunshine, wind, rain etc.
Measuring the weather - Devices
Rain gauge - Precipitation
Maximum/ Minimum thermometer - Temperature
Sunshine recorder - Sunshine
Wind vane - Wind direction
Barometer - Air pressure
Anemometer - Wind speed
Hygrometer - Humidity
How to measure cloud cover
Hold a card with 8 equal squares up to the sky + count the amount of sqaures filled.
1 square = 1 okta
More oktas = more cloud coverage
Cirrus - Characteristics
- Found at high altitudes
- Wispy, with a silky sheen (tufts of hair)
- White, but can take on colours of sunset / sunrise.
- Made up of ice crystals
Cumulus - Characteristics
- Detached, individual, cauliflower-shaped clouds.
- Usually spotted in fair weather conditions.
- Tops of these clouds = mostly brilliant white tufts when lit by the Sun
- Base is usually relatively dark.
Stratus - Characteristics
- Low-level layers
- Fairly uniform grey or white colour.
- Often overcast days
- Can persist for long periods of time.
- Sometimes appear at surface of fog/mist
Cumulonimbus - Characteristics
- Menacing looking
- Extend high into the sky in towers or plumes.
- Thunderclouds.
- Can produce hail, thunder and lightning.
- Base of the cloud is often flat, + dark wall-like feature hanging underneath,
- May only lie a few hundred feet above the Earth’s surface.
What type of weather do cirrus clouds bring?
- Often form in advance of a warm front.
- Often indicate a change in weather.
What type of weather do cumulus clouds bring?
- Cumulus indicates fair weather, often popping up on bright sunny days.
- Can however, grow into cumulonimbus
What type of weather do stratus clouds bring?
- Little to no rainfall but if it is thick enough, it can produce light drizzle.
- This drizzle can also fall in the form of light snow if cold enough
What type of weather do cumulonimbus clouds bring?
- Extreme weather (Heavy torrential downpours, hail storms, lightning and even tornadoes)
- Usually dissipate within an hour once showers start falling (Short-lived, heavy rainfall)
Hygrometer - How it works
- Two thermometers (wet and dry thermometer)
- Dry thermometer measures current temperature
- Wet thermometer covered with a muslin cloth submerged in water.
- If air is extremely saturated (no water will evaporate from cloth bc air can’t hold more humidity)
- If air isn’t humid, water evaporates from cloth
- Evaporation = endothermic –> therefore temperature of wet thermometer decreases
- Use of relative humidity chart to find percentage in relative humidty using differences in humidity.
Anemometer - How it works
- Measures wind speed (km/h)
- 3 or 4 metal cups that can rotate on a vertical shaft.
- When there is wind, the cups rotate
Faster wind = Faster rotation
- Number of rotations recorded on a meter = speed in km/h
Where should an anemometer be placed?
- Placed far away from trees/ buildings.
- Can slow down winds / buildings can channel air through narrow passages between two buildings.
- Placed high up
- (avoids interference by animals)