Weather Flashcards
What are the main weather elements?
Precipitation (rain, hail, sleet & snow) Temperature Wind Speed and Wind Direction Sunshine Cloud Cover Visibility Air Pressure Humidity
How do you measure temperature?
Thermometer (maximum & minimum) in *C, in the shade often in a Stevenson Screen
What is a Stevenson Screen?
White, slatted box. Sits on grass, with long legs.
How do you measure precipitation?
Rain gauge in milimetres (mm), partly sunk into the ground for stability in the wind, away from tress and buildings
How do you measure air pressure?
Barograph in milibars (mb), indoors
How do you measure wind speed?
Anemeter in knots/ force scale, attatched to a building or used manually
How do you measure wind direction?
Wind vane in N,S,E,W, high up on a building
How do you measure sunshine?
Campbell Stokes Sunshine Recorder in hours, in the open-clear view of sky
How do you measure cloud cover?
Human eye in oktas
How do you measure visibility?
Observation in kilometers (km)
How do you measure humidity?
Hygrometer (wet & dry bulb thermometer) in *C
How does latitude affect temperature in the UK?
Areas further north or south receive less sun because sun’s rays pass through more atmosphere and spread out
How does aspect affect temperature in the UK?
Places facing south are warmer because:
they receive more sun
sheltered from cold winds
How does relief affect temperature?
Temperatures decrease by 1*C every 100 metres.
How does distance from the sea affect temperature?
warmer in winter in west of UK because:
Atlantic ocean milder than land surface
warm ocean current (North Atlantic Drift) makes temperatures milder
What is relief rainfall?
Upland areas receive more rain than lowland areas. Moist air blows reaches hills and cools down, condenses then rains.
What are the air masses which affect the UK?
Artic maritime (Am) Polar maritime (Pm) Tropical maritime Tm) Tropical continental (Tc) Polar continental (Pc)
What does artic maritime bring?
Very cold and moist air
What does polar maritime bring?
Cold and moist air
What does tropical maritime?
Warm and wet air
What does tropical continental bring?
Warm and dry
What does polar continental bring?
Cold and dry
Explain the formation of a depression
Where the Tm and Pm air masses meet is called a front
Warm air rises over the cold air, creating low pressure
Wind blows around and towards low pressure in anticlockwise direction
What is a warm front?
Warm air rising over cold air
What is a warm sector?
Occupied by Tm air
What is a cold front?
Where cold air undercuts warm air
What is an isobar?
Lines joining places with same air pressure
What is an occluded front?
Cold front meets warm front
What clouds appear before warm front?
Cirrus
What clouds appear during warm front?
Nimbostratus
What clouds appear during warm sector?
Stratus
What clouds appear during cold front?
Cumulonimbus
What clouds appear after cold front?
Cumulus
Describe rainfall before warm front
Dry
Describe rainfall during warm front
Prolonged rain
Describe rainfall during warm sector
Scattered showers
Describe rainfall during cold front
Heavy rain
Describe rainfall after cold front
Scattered showers
What are features of an anticyclone
Wind blows clockwise parallel to isobars
Isobars are far apart, meaning light/calm winds
Sunny clear skies
Dense air sinking and no air rising
Describe the weather in an anticyclone in Summer.
- Dry (air is sinking)
- Light winds or calm (isobars are widely spaced)
- Sunny, few clouds (air is sinking)
- Hot during the day (there are few clouds)
- Cool at night (there are few clouds)
- Early morning dew
- Occasional thunderstorms
- Costal mist
Describe the weather in an anticyclone in Winter.
- Dry (air is sinking)
- Light winds or calm (isobars are widely spaced)
- Sunny, few clouds (air is sinking)
- Cold during the day (there are few clouds)
- Frost at night (there are few clouds)
- Early morning fog, especially on low ground.
How does aspect affect rainfall?
The hillsides which face the moist winds receive the most rain which in the UK is the west facing slopes because the AO is to the west. On the other side of the hill the air sinks and warms . Very little water vapour will condense meaning there are fewer clouds and less rain (called a rainshadow area)
How does distance from the sea affect rainfall?
The winds that reach the west coast are usually full of water vapour and bring lots of rain because most of the water vapour in our air is evaporated from the Atlantic Ocean . As the winds move eastwards they drop most of their water so bring less rain to places further east.
What is latitude?
Latitude describes how far a place is from the equator.
What is aspect?
Aspect is the direction in which the land faces.
