Geog~Ch.6 Atmospheric Conditions Flashcards
What gases does the atmosphere consist of?
78% nitrogen
21% oxygen
0.9% argon
0.03% carbon dioxide
Function of the atmosphere?
Holds heat from the sun while also blocking the earth from much of the sun’s incoming ultraviolet radiation
What is the lowest layer if the atmosphere?
The troposphere
What happens at the troposphere?
Weather conditions change constantly within this layer
Insolation
Incoming Solar Radiation
Two factors that affects the amount of insolation absorbed by the earth’s surface are:
- Angle of the sun’s rays
2. The content of the atmosphere
3 factors influencing the angle at which sun rays strike the earth
1 the location
- Time of day
- Season
Why is the temperature at its highest at the equator?
Because the suns rays are most direct at the equator
What tropics do the sun move between?
Tropics of Cancer
Tropics of Capricorn
The content of the atmosphere is affected by ____ and ____
- Reflection
• clouds and surface of the earth reflect energy back into space.
• Albedo - light reflect heat, dark absorb heat - Absorption
Two energy transfers are:
Global winds
Ocean currents
Wind is :
Air moving from a high pressure area to a low pressure area.
High pressure is the result of
Descending air i.e cold air falling due to heaviness
Low pressure is the result of
Rising air i.e warm air rises due to lightness
Warm winds blow from the ______.
Equator
Cool winds blow from the ______
High latitudes
Latitude ?
Gives the location of a place on earth north or south of the equator.its the angular distance from the equator
The global wind pattern is also known as :
The general circulation
Explain how the global winds system works:
- Equator ➡️ warm air rises = zone of low pressure
- 30’ north or south ➡️ the warm air cools= heavier= sinks = area of high pressure
- some of this air blows back towards the equator (trade winds)
- 60’ north and south ➡️ some warm air meets cold polar air = form polar fronts = low pressure
- 90’ at the poles ➡️ cold air = zone of high pressure
- process continues over and over creating convection currents that keeps the atmosphere in constant motion.
Name the 3 wind belts
• Tropical Easterlies
0-30' trade winds
• Prevailing Westerlies
30-60' westerlies
• Polar Easterlies
60-90' polarWhat is the Coriolis effect?
when the global winds are deflected due to the earth’s rotation.
Zones that separate the 3 major wind belts
- the doldrums (equator)
- the horse latitudes ( still dry 30’)
- the polar fronts (60’)
Factors influencing the ocean currents:
- rotation of the earth
- influence of the winds
- difference in temperatures in oceans
Warm currents flow from :
From areas of low latitude to high
Cold currents flow from areas of
High to low latitude
Examples of warm currents:
- the gulf stream
* North Atlantic drift
Examples of cold currents:
- labrador current
* greenland current
Advantages of ocean currents:
- ice free coasts
- warmer winds
- good fishing grounds
Disadvantages of the ocean currents:
- creation of ice bergs
- colder winds
- hard sailing conditions
What is the atmosphere?
The atmosphere is a thin layer of gases surrounding the earth.(referred to as the air)
What is an air mass?
A large body of air with similar temperature,pressure and moisture levels throughout.
Maritime air is generally:
Moist and rain
Continental air is generally:
Dry
What is a front?
Boundaries between two air masses
List 4 air masses:
- Maritime polar
- Maritime tropical
- continental polar
- Continental tropical
Continental polar (cP)
North-east Europe
Dry cold
Frosty nights
Maritime polar (mP)
North Atlantic
Cold wet air
Showers
Continental tropical (cT)
Sahara desert
Dry sunny
Maritime tropical (mT)
Azores
Thunderstorms in summer
Heavy rainfall in winter
Arctic (A)
North pole
Cold
Whats a cold front?
A cold front forms when a cold air mass moves into a warm air mass.
Explain how a cold front works:
Cold air is heavy so it pushes underneath warm air = forces warm air up to cool and condense ➡️ clouds
The air behind is colder&drier than the air ahead of it
Whats a warm front?
A warm front forms when a warm air mass moves into a cold air mass.
Explain how a warm front works
Warm air (less dense) slides over colder air. ➡️ rain Air behind a warm front = warm moist = high pressure =clear sky
High pressure systems are also called:
Anticyclones
What causes an anticyclone?
High pressure is a result of cold air descending on the earth’s surface.
High pressure: air moves from an area of _____ pressure to an area of ____ pressure.
High ↪️ low (causes winds)
Characteristics of a high pressure system
- clockwise winds
- no fronts
- warm air descends
- slow
- isobars are well spaces = calm winds
- forms over land
Weather with high pressure system
- clear cloudless sky
- calm dry
- summer hot
- winter cold nights due to clear skies
Lows pressure systems are also called:
Cyclones
What causes a low pressure system ?
Lows develop as a result of warm air rising
In a low pressure system air moves from an area of ___ pressure to an area of ___ pressure
High ↪️ iow (as winds blow into a low,air descends up = clouds & precipitation
Characteristics of a low pressure system
- anticlockwise
- air rises temperature falls
- isobars close together = strong wind
- cloud
- cyclonic rainfall
- warm tropical air meets polar air over the Atlantic
Weather with low pressure
- cloudy skies
- windy wet
- unpredictable
What is a depression?
A depression is an area of low pressure
That develops when a warm front meets a faster moving cold front.
Explain how a depression works:
Warm air=area of low pressure
Cold air swirls in an anticlockwise direction = warm air surrounded by colder air
= 2 fronts develop, warm front in front of cold
Faster colder air catches up with the colder air ahead= warm sector pushed up ➡️ occlusion
What’s weather?
Weather is the day to day state of the atmosphere over any place on the earth’s surface
What is a weather forecast?
Global patterns of weather
Name the 7 different elements of weather
- temperature
- humidity
- atmospheric pressure
- precipitation
- wind speed and direction
- sunshine
- cloud amounts
Whats a meteorologist
A person who studies and forecasts (predicts) weather
Whats meteorology?
The study of weather
Isobars?
Lines on a weather map which connect places of equal atmospheric pressure.
Isotherms?
Lines on a weather map which connect places of equal temperature
Isohyets?
Lines on a weather map which join places with equal rainfall
Isohels?
Lines on a weather map showing equal sunshine
Whats temperature?
Measures how hot or cold the air is
What is a thermometer?
Used to measure temperature
•mercury or alcohol
• +temperature ➡️ liquid rises up
• -temperature ➡️ liquid falls
What measures the highest temperature for the day?
Maximum thermometer (mercury) The index stays at the highest point it reached a day
What measures the lowest temperature for the day?
Minimum thermometer (alcohol) Index stays at lowest point
Mean temperature?
Average
Day = maximum+minimum➗2
Temperature range?
Highest - lowest = range
What is humidity?
The amount of water vapour and moisture in air.
When air has absorbed as much moisture as it can , its ______
Saturated
Relative humidity?
Amount of water vapour in air compared to the amount it would contain if saturated. (Hygrometer)
Hygrometer:
Mix of wet and dry thermometers
What instrument is used to measure humidity
Hygrometer
What instrument is used to measure wind force (speed)
Anemometer
Instrument for measuring sunshine?
Campbell stokes meter
Instrument for atmospheric pressure?
Barometer
Instrument for speed direction?
Wind vane
Instrument for precipitation?
Rain gauge
Unit of measurements for atmospheric pressure
Millibars
3 types of barometers?
Mercury
Aneroid
Barograph
Explain how one type of barometer works
Barograph: connects a barometer to an inked pen resting on a drum which rotates
Explain a wind vane
Has a horizontal arm with arrow at 1 end and a bigger tail on other.
Wind blows tail around arrow points at de direction the winds cominh
Explain how a campbell stokes sunshine recorder works
Made up o a solid glass sphere that focuses the suns rays onto a sensitive strip of paper slotted into the semi circular frame behind the ball.
Suns rays ♨️ the paper and as the sun moves during the day, the scorch marks moves along too
What is a stevenson screen?
Its a meteorological screen that shields and stores weather instruments.
Describe how a stevenson screen looks
White (reflects sunlight) Louvered (slanted) panels ➡️ keep out the direct rays of sun and rain but allows air to circulate freely into the box ➡️ box raised on stilts 1.4m off ground ( no effect from the ground temperature
Use of weather in everyday life
Fishing Airplanes Sports Tourists Farmers
Name 3 main types of clouds
- stratus
- cumulus
- cirrus
Stratus clouds:
Like a blanket ↔️ stretches out across sky & blocks sun
Overcast day or steady rain
Cumulus clouds:
Like puff of cotton
Heavy showers
Cirrus clouds :
Wispy & high up & scattered
Fair weather
List 3 rainfall types
Convectional rainfall
Cyclonic / frontal rainfall
Relief rainfall
