Geography Year 4 W&C Flashcards
Define weather
Weather refers to the conditions of the atmosphere at a specific place over a relatively short period of time.
Name the Six elements of
weather
- temperature
- relative humidity
- clouds
- rainfall
- air pressure
- wind
Define climate
Climate refers to the atmospheric conditions of a specific place over a considerable period of time, usually 30 to 35 years.
define Temperature and what determines it
- temperature is the degree of hotness or coldness of a place
- this is determined by the energy from the sun
which reaches the earth.
How does the atmosphere heat up
- energy from the sun travels through the atmosphere
- it’s absorbed by the earth’s surface
- the earth’s surface warms up as a result
- the warming of the earth’s surface heats the atmosphere
- Mean daily temperature
- Diurnal temperature range
- Sum of hourly temperature / 24
= Maximum daily temperature - Minimum daily temperature
- Mean monthly temperature
- Mean annual temperature
= Sum of mean daily temperatures in the month / Number of days in the month
= Sum of mean monthly temperatures in the year / 12
Annual temperature range
= Maximum mean monthly temperature - Minimum mean monthly temperature
define isotherms
Isotherms are a type of contour line that
connects points of equal temperature on a map.
what do isotherms do?
-isotherms help visualize the temperature distribution in a region
-isotherms show how much temperature changes per unit distance (e.g., kilometre)
-isotherms indicate the direction of temperature changes
closely spaced isotherms VS widely spaced isotherms
-closely spaced isotherms indicate rapid temperature change over small distances
VS
-widely spaced isotherms indicate slow temperature change over small distances
What are the 5 factors affecting temp?
- latitude
- altitude
- distance from sea (maritime and continental effect)
- cloud cover
- microclimatic factors
what are latitudes
- Latitudes are imaginary lines running east-west across the globe
- The equator divides the globe into the northern and southern hemispheres
- Latitudes indicate how far a location is from the equator
earths tilt VS angle of incidence
- The spherical shape of the Earth causes variations in solar radiation (insolation)
- Insolation is the incoming solar radiation that heats the Earth’s surface
- Earth tilts at 23.5° on its axis, affecting how the sun’s rays strike different parts of the world
latitude linked with temp
talk abt higher vs lower latitudes and northern hamisphere tilt
- The angle of incidence is the angle at which solar radiation hits the Earth’s surface
- Higher latitudes have a lower angle of incidence → less concentrated insolation → lower temperatures
- Lower latitudes have a higher angle of incidence → more concentrated insolation → higher temperatures
- When the northern hemisphere is tilted towards the sun, it receives more sunlight, leading to higher temperatures (Spring → Summer)
Temperatures at lower vs high altitudes (super simple)
lower altidue -> warmer
higher altitude -> cooler
altitudes w temp (distance from sea) 3 POINTSSS
- Greater concentration of atmospheric gases and particles (e.g., water vapour, carbon dioxide, dust) near the Earth’s surface → better absorption of shortwave radiation
- Thinner concentration of gases and particles at higher altitudes → less heat trapped → lower temperatures
- Earth’s surface absorbs shortwave radiation from the sun → emits longwave radiation (heat) → higher altitudes are further from the surface, the source of longwave radiation → lower temperatures
altitudes -> density -> absorbtion
Higher altitudes have lower air density and pressure, reducing the ability to absorb and radiate heat, resulting in lower temperatures.
what is the envrionmental lapse rate?
Temperature decreases by 6.5°C for every 1000m increase in altitude.
Which heats up faster and slower? land or sea
and what does this affect?
- Sea heats up and cools down more slowly than land
- Difference in heating/cooling affects temperatures of coastal vs inland areas
How does proximity to the sea affect temperature? SPECIFICALLY coastal areas vs inland areas
- Coastal areas have lower summer temperatures compared to inland areas
- Coastal areas have higher winter temperatures compared to inland areas
DUE to the moderating effect of onshore winds - Coastal areas have smaller temperature ranges compared to inland areas
- Land heats up and cools down faster than the sea
Why are coastal areas cooler in summer? and what effect is this?
Maritime effect in the summer.
- Land heats up faster than the sea
- Cool winds from the sea lower coastal temperatures
- Coastal areas are cooler in summer compared to inland areas
Why are coastal areas warmer in winter? and what effect is this?
Maritime effect in the winter
- Land cools down faster than the sea
- Warmer winds from the sea raise coastal temperatures
- Winds lose moderating effect as they move inland
What is continental effect?
- The continental effect occurs in inland areas, where large land surfaces influence the climate.
- Causes larger temperature ranges due to the lack of sea influence.
- Inland areas experience hotter summers and colder winters.
- Coastal areas, in contrast, have cooler summers and warmer winters due to the maritime effect.
What is the difference between the maritime and continental effect?
- Onshore winds create a maritime effect in coastal areas, leading to smaller temperature variations
- Inland areas experience a continental effect, with larger temperature ranges due to the lack of moderating sea influence
what is humidity and what is it measured as?
- Humidity is the amount of water vapour in the air.
- Higher humidity → feels wetter outside.
- Usually measured as relative humidity in weather reports.
How do clouds affect daytime temperatures?
More clouds → reflect incoming solar radiation → lower day temperatures.
Fewer clouds → land absorbs more solar radiation → higher day temperatures.
higher vs lower humidity how deos it affect cloud cover?
Higher humidity → more clouds form as water vapour condenses into droplets.
Lower humidity → fewer clouds due to less condensation.
How do clouds affect nighttime temperatures?
More clouds → trap outgoing heat → higher night temperatures.
Fewer clouds → heat escapes into space → lower night temperatures.
What is a microclimate?
- Microclimate refers to the climate of a small area or specific environment/place (e.g., a city, rural town, forest, or open space).
- These areas can have different surfaces, influencing their local climate.
Why do deserts have a large diurnal temperature range?
- Low humidity → little cloud cover to moderate temperatures
- More solar radiation reaches the earth’s surface during the day, causing excessive heating of the land → very hot daytime temperatures
- Few clouds → longwave radiation escapes quickly into space → rapid cooling at night
Result: large diurnal temperature range (very hot days, very cold nights)
Why do equatorial regions have a small diurnal temperature range?
- High humidity → more clouds form, moderating temperature fluctuations
- Clouds reflect some incoming solar radiation, reducing heating of the land → lower day temperatures
- Clouds trap outgoing longwave radiation, reducing heat loss to space → higher night temperatures
Result: small diurnal temperature range (less difference between day and night temperatures)
What is the urban heat island effect?
- The urban heat island refers to slightly higher temperatures in urban areas compared to the surrounding countryside.
- Urban areas are generally warmer due to human activity, buildings, and surfaces that absorb and retain heat more than rural areas.
What is relative humidity?
- Relative humidity refers to the proportion of water vapour in the air compared to the maximum amount the air can hold at a specific temperature.
- Expressed as a percentage.
- Saturation occurs when the air carries the maximum water vapour it can hold at that temperature (i.e., relative humidity at 100%).
What factors affect relative humidity?
- Availability of water sources → More water vapour available increases relative humidity.
- Availability of vegetation → Water vapour can also be contributed by the transpiration process → vegetation loses water in the form of water vapour through the stomata of their leaves
How does temperature affect relative humidity?
temperature increases → relative humidity decreases (if the amount of water vapour remains constant).
Air gains heat → expands → Warm air can hold greater amounts of water vapour due to larger spaces between air molecules → with the same amt of water vapour in a bigger air parcel, RH is lesser
How does convectional rain form?
TO LEARN IN DEPTH BY DRAWING
- Hot air rises from the ground, cooling and condensing as it reaches higher altitudes.
- The condensed water vapour forms towering cumulonimbus clouds.
- When the water droplets in the clouds become too heavy, they fall as rain.
Where is convectional rain founf, what issit accompanied by and what weather conditions are associated with it?
- Common in tropical and temperate regions during summer, especially on hot days.
- Heavy rain that does not last long.
- Often accompanied by lightning and thunder.
What is the dewpoint/saturation point?
The dewpoint is the temperature at which air can no longer hold all its water vapour.
At this point, some water vapour condenses into liquid water.
How does relief rain occur?
TO LEARN IN DEPTH BY DRAWING
- Relief rain occurs when moist onshore air is forced to rise up the windward slope of a mountain.
- As air rises, it cools with increasing altitude, leading to condensation of water vapour into water droplets.
- When water droplets become too heavy to stay suspended, relief rain falls on the windward slope.
what weather conditions are associated with relief rain?
- light rain
- long durations
- when mountain faces sea, MOST LIKELY its RELIEF RAIN
Why does rainshadow occur (relief rain) ? + as air descends….
On the leeward side of the mountain, little or no rain occurs.
As air descends, its temperature increases and relative humidity decreases, preventing rainfall from forming.
How does temperature affect air pressure?
- Warm air expands, becomes less dense, and rises, causing low pressure below.
- Cold air, being denser, sinks and exerts high pressure below.
- Higher temperatures lead to lower air pressure as air molecules spread apart.
What is air pressure? air pressure and altitude trend
- Air pressure is the weight of air exerted on any exposed surface.
- Air pressure is highest near the ground because of the weight of overlying air.
- Air pressure decreases with increasing height due to less overlying air at higher altitudes.
What are isobars?
- Isobars are lines that connect points of equal atmospheric pressure on a map.
- Isobars help to show the distribution of air pressure over a region.
How is air pressure measured?
- Air pressure is measured using a barometer.
- The unit of measurement is millibars (mb).
How does altitude affect air pressure?
- As altitude increases → air becomes thinner → places at higher altitudes experience lower air pressure.
- Places at lower altitudes experience higher air pressure due to more overlying air.
What are the 2 types of Local winds?
Sea breeze
Land breeze
Sea Breeze
- During the day → Coastal land heats up faster than the sea.
- air over the land heats up → expands and rises → low pressure forms over the land.
- Sea heats up slower, so the air over it is cooler → high pressure forms over the sea.
- Sea breeze blows from high pressure over the sea → low pressure over the land.
- Sea breeze → cooling effect at coastal areas.
Land Breeze
- At night, coastal land loses heat faster than the sea.
- Cooler air over the land → sinks → high pressure forms over the land.
- Sea retains heat longer → warmer air over the sea rises → low pressure forms over the sea.
- Land breeze blows from high pressure over the land → low pressure over the sea.
- Land breeze → cooling effect on the sea.
- Land breeze is generally weaker than the sea breeze due to slower cooling of the sea.
What is the 1 regional wind?
Monsoon winds!
All about the Coriolis effect and deflection!
- Coriolis effect → Causes deflection of winds.
- Winds traveling to the Northern Hemisphere → deflected to the right.
- Winds traveling to the Southern Hemisphere → deflected to the left.
- The Coriolis effect is strongest at the poles and weakest at the equator.
- Angle of deflection → Increases with distance from the equator.
What are Monsoon Winds?
- Monsoon winds → Seasonal movements of large air masses across the Earth.
- Result of extreme heating and cooling of large landmasses.
- Winds are deflected due to the Coriolis effect.
Bring us through the Southeast and Southwest Monsoons [Jun to Sept]
- Cold air over Northern Australia → contracts, sinks, creates high pressure.
- Warm air over Central Asia and Northwest India → expands, rises, creates low pressure.
- Southeast monsoon → Winds blow from high pressure in Australia to low pressure in Central Asia (Southern Hemisphere).
- Winds cross the equator → deflected to the left due to Earth’s rotation → Southwest monsoon in Northern Hemisphere (India/Central Asia).
Northeast and Northwest Monsoons [Oct to Jan]
- Central Asia and Northwest India → lose heat rapidly in winter → high pressure forms.
- Southern Hemisphere → warm air expands, creating a low pressure area.
- Winds blow from high pressure in Central Asia to low pressure in Australia.
- In the Northern Hemisphere → Winds are deflected to the right, arriving in India/Bangladesh as Northeast Monsoon.
- Winds cross the equator → deflected to the left in the Southern Hemisphere → arrive in Australia as Northwest Monsoon.
Define wind
Wind is a parcel of air that moves from high pressure to low pressure.
