Weather and climate combined

Wind vane

Measures wind direction.

Convection

Process of heat transfer by the circulation or movement of a liquid or a gas.

Condensation

The process by which molecules of water vapor in the air become liquid water.

Evaporation

The process by which water molecules in liquid water escape into the air as water vapor.

Weather

Day-to-day changes in atmospheric conditions, including temperature, air pressure, humidity, wind, cloud coverage, or precipitation.

Climate

Long-term average of weather in an area.

Polar

Dry, cold climate zone above 60 degree latitude.

Temperate

Seasonably variable climate zone between 40 and 60 degrees latitude, north or south of the equator.

Tropical

Warm, moist climate zone near the equator.

Air mass

Large body of air with the same temperature and humidity.

Front

Where two different air masses meet.

Humidity

Moisture in the air.

Jet stream

Fast moving stream of wind where cold, polar air meets warm air from the equator.

Drought

A long period of unusually dry weather.

Anemometer

Measures wind speed.

Barometer

Measures air pressure.

Air pressure

The pressure caused by the weight of a column of air pushing down on an area.

Atmosphere

The envelope of gases that surrounds Earth.

Precipitation

Any form of water that falls from clouds and reaches Earth's surface.

Water cycle

The continual movement of water among Earth's atmosphere, oceans, and land surface through evaporation, condensation, and precipitation.

Warm front

Warmer air; light and steady precipitation; move southwest to northeast.

Cold front

Colder air, heavy rain, thunderstorms, snow.

What is weather?

It refers to the state of the atmosphere at a particular place and time, described using variables including (air temperature, cloud cover, precipitation, wind speed, wind direction)

What is climate?

It is the average state of the atmosphere at a particular place over a long period of time, typically 25 years or more. (tropical equatorial, tropical monsoon, cool temperate)

Tropical equatorial description and location?

• Generally high temperatures all year round about 27°C

• Small annual temperature range of about 2-3°C

• High annual precipitation of more than 2000mm

• Precipitation falls evenly throughout the year

• Location is between 10°N and 10°S of the equator

• Havana, Cuba and Singapore

Tropical monsoon climate description and location

• Generally high temperatures all year round, of about 25°C

• Small annual temperature range of about 3-4°C

• High annual precipitation of about 1500mm

• Distinct wet and dry seasons

• Location is between 5°N and 30°N of the equator and 5°S and 30°S of the equator

• Chittagong, Bangladesh, Kochi, India

Cool temperate climate description and location

• Four distinct seasons of spring, summer, autumn, and winter

• Large annual temperature range of about 21°C

• Annual precipitation is between 300-900mm

• Precipitation falls evenly throughout the year

• Location is between 45°N and 60°N of the equator and 45°S and 60°S of the equator.

• London, United Kingdom, Paris, France

What are climate hazards?

• Climates are changing due to natural and human-induced causes

• Predictable weather patterns in many places are now beginning to change and becoming unpredictable

• Extreme weather events, such as heat waves, droughts, floods, cyclones, and wildfires are expected to occur more often or with greater severity

• These can impact natural and human system significantly (ecosystem and agriculture)

• Climate change can destroy crops and disrupt food production, affect commuting and travelling, leading to great economic losses

Air temperature variations over time in a day:

• Mainly due to the Earths rotation( anti clockwise) on its own axis.

• Temperature varies over time in a day as when the Earth rotates, the side of the Earth that faces the Sun experiences day and receives solar radiation, thus it experiences higher temperatures

• In the morning and evening, the temperature is lower because the sun’s rays are less direct thus solar radiation is spread over a larger area and becomes less concentrated

• Temperature is high at noon where the sun is directly overhead and solar radiation is more concentrated over a smaller area

• As the Earth continues rotating, this side will eventually face away from the Sun and experience night time where it does not receive solar radiation, thus experiences lower temperatures.

Air temperature variations over time in a year

• Mainly due to the Earth’s revolution around the Sun

• Earth’s axis is tilted 23.5c

• As the Earth revolves around the Sun, hemisphere will receive different amounts of solar radiation across the year

Latitude and definition

• Imaginary lines that forms circles around the Earth, parallel to the Equator

• At the global scale, temperatures are lower at higher latitudes

• Due to the Earth’s spherical shape, the angle at which the Sun’s rays strike the Earth’s surface (solar angle) varies at different parts of the Earth

• The higher the latitude, the smaller the solar angle, therefore solar radiation is less direct, is spread over a large area is less concentrated, leading to lower temperatures

  • E.G: Beijing (40N) has temperatures averaging 12C, while SG (1N) has temperatures averaging 29C

  • Singapore is within the tropics, with high annual temp of 27

Altitude and definition

• Vertical height above sea level

• At a local scale, temperatures are lower at higher altitude

• At higher altitudes, air is less dense and air pressure is lower as gravity pulls most of the air molecules towards the ground surface

• With fewer air molecules, air has a lower ability to absorb and radiate heat, leading to lower temperature

  • E.G: Average temperatures at Genting highlands (altitude of 1700mm above sea level) is about 21C. Average temperatures in the surrounding areas which are at sea is about 32C

What factors affect air temperature at specific sites?

• Type of surface

• Distance from the sea

Type of surface

• Dark surfaces (exposed soil and forests) generally absorb more solar radiation and radiate more heat, resulting in higher temperatures

• Light-coloured surfaces (clouds and snow) generally reflect more solar radiation and radiate less heat, resulting in lower temperatures

• Urban areas tend to have higher temperatures than rural areas because:

  • Urban areas comprise larger areas of dark surfaces (roads) which absorbs solar radiation and radiate more heat than forests and water-bodies

• Glass-covered skyscrapers reflect sunlight to the ground surface, increases absorption of solar radiation and heat radiation by ground surfaces

  • E.g: Night-time temperatures at Singapore’s Central Business District were found to be 2c warmer than the areas near Macritchie reservoir, which has very dense vegetation

Distance from the sea

• Coastal areas experience CSWW due to maritime effect, lower annual temperature range

• Inland areas experience WSCW due to continental effect, higher temperature range

• Sea heats up and cools down more slowly than land (due to thermal properties as land is solid, sea is liquid)

  • During winter, the sea is warmer than land, warming the air along coastal areas

  • During summer, the sea is cooler than land, cooling the air along coastal areas

• Inland areas do not experience this moderating influence of the sea, and instead experience the continental affect

  • E.g: Anchorage, a coastal city in Alaska, USA, has a lower annual temperature range of 23c, while Fairbanks, an inland city in Alaska USA, has a higher annual temperature range of 40c

Water cycle

1. Evapotranspiration, plants give out water

   vapour through transpiration, Sun’s heat causes water from water bodies to evaporate, forming water vapour

2. Condensation, as water vapour rises, it cools and condenses into tiny water droplets at dew point temperature and clouds are formed

3. Precipitation, when the water droplets in the clouds become big and heavy enough, they fall to the ground as precipitation

4. Infiltration, water on the ground surface infiltrates the subsurface of soil and rock

5. Surface runoff, water flows over the ground surface as surface runoff and enters a body of water

6. Groundwater flows, below the Earth’s surface, water moves horizontally above the impermeable rocks as groundwater flows.

How does water move on and below the earth’s surface

Type of soil

Infiltration rate and groundwater flows are faster in soil which has larger pores (sandy soil) than in soil which has smaller pores(clayey soil).The larger pores allow more water to infiltrate, allowing the water to move much more quickly.

How built-up an area is

• Infiltration rates are lower in built-up areas where ground surfaces are covered in concrete roads which have tiny pores.

• The speed of surface runoff is higher on smoother ground surfaces such as on roads and pavements in built-up areas, due to fewer obstructions and lesser friction.

Presence of natural vegetation

• Infiltration rates and groundwater flow are faster where there is vegetation as the roots of plants loosen the soil, creating more open spaces of surface runoff to pass through

• The speed of surface runoff is lower on vegetated areas as the stems and roots of grasses and plants act as barriers and increase the surface roughness

gradient of surface runoff

the speed of surface runoff is higher on steeper slopes than on gentler slopes as the force of GRAVITY acting on the earth is higher

relative humidity

• refers to the ratio of the amount of water vapour in the air to the maximum amount of water vapour the air can hold at a given temperature

• temp increase, rh decrease, rh increase, temp decrease

• RH = actual amount of water vapour present in air/ max amount of water vapour the air can hold x 100

• when temperature increases, the amount of water

• vapour that air can hold increases, relative humidity therefore decreases

• relative humidity is at 100 when air holds the max amount of water vapour, air is saturated

• when RH exceeds 100, condensation occurs when

  • more water vapour is added to the air thru evaporation

  • air temperature drops

how are clouds formed

as air rises up in the atmosphere, it cools, reducing the amt of water vapour it can hold

eventually, amt of water vapour in the air exceeds the max amount of water vapour the air can hold (rh becomes 100 and air is saturated)

at this dew point temperature, air condenses into water droplets on CONDENSATION NUCLEI

condensation nuclei (dust and ash particles from volcanoes) provides surfaces where water vapour can change into water droplets or solid ice crystals and form clouds

how is rain formed

water droplets in the clouds collide and coalesce and become bigger and heavier

the water droplets fall to the earth as raindrops once they are large and heavy enough over 5mm

sometimes these droplets break apart as they fall

rainfall may start as snow/ice crystals but melt when they fall into warmer air

convectional rain

in the day, heat from the sun is absorbed by the land, and the air above it gains heat

the warm air rises and cools, and condenses on condensation nuclei at dew point temperature. clouds are formed

water droplets in the clouds collide and coalesce, and when they become large and heavy enough, they fall to the ground as rain

e.g: frequent afternoon thunderstorms in singapore

relief rain

prevailing winds pick up moisture over the sea, and pushes the moist air up the windward side of the mountain.

the rising moist air cools and condenses on condensation nuclei or dew point temperature, clouds are formed.

water droplets in the clouds collide and coalesce, and when they become large and heavy enough, they fall to the ground as rain on the windward side.

as most of the moisture has fallen on the windward side, the leeward side experiences dry descending and is thus dry.

e.g: The windward side of the sierra nevada mountain ranges, USA, receives higher rainfall, and thus has lush forests. The leeward side is hot and dry, creating the Death valley desert.

how are winds formed

wind is the horizontal movement of air across the earths surface

it occurs due to the unequal distribution of air temperature, which results in an uneven distribution of PRESSURE GRADIENTS:

The further away you are from the Earth’s and its gravitational force, the fewer gas molecules are present in the atmosphere

In places with higher temperatures, air is heated, becomes less dense, and rises. This results in a void and lower atmospheric pressure. In places with lower temperatures, air cools, becomes denser, sinks, which results in higher atmospheric pressure.

the difference in pressure between two areas forms a pressure gradient

air moves from the area of higher pressure to the area of lower pressure to fill int he void, hence wind is formed

what determines the speed of wind

1. strength of pressure gradient

   smaller pressure gradient: smaller difference in pressure between two areas, leading to slower wind speeds. larder pressure gradient: bigger difference in pressure between two areas, faster wind speeds.

2. friction

   as moving air comes in contact with variations in the earths surface, it experiences frictional drag which reduces wind speed. the affect of frictional drag is greatest where there is uneven relief and rough surface on land. (valleys/mountains)

why do wind direction vary across the earths surface on a local scale

land breeze - night

in the night, both land and sea lose heat through longwave radiation.

the sea and the air above it lose heat slowly. the warmer air is less dense and rises, forming lower pressure over the sea.

on the other hand, the land and the air above it lose heat quickly. the cooler air is denser and sinks, forming higher pressure over land.

air moves from an area of higher pressure over the land to lower pressure over the sea, forming land breeze.

sea breeze - day

in the day, heat from the sun is absorbed by both the land and the sea through shortwave radiation.

the land and the air above it gains heat quickly. the warmer air is less dense and rises, forming lower pressure over the land.

on the other hand, the sea and the air above it gains heat slowly. the cooler air is denser and sinks, forming higher pressure over the sea.

air moves from an area of higher pressure over the sea to lower pressure over the land, forming the sea breeze.

why does wind direction vary across the earths surface on a regional scale

unequal distribution of air temperature across the earths surface results in varied pressure zones.

air moves across the earth over different regions from high pressure to low pressure zones.

as wind travel over large distances, they are deflected by the coriolis force. this occurs due to the earths rotation
northern - winds deflect to their right

southern - left

northeast monsoon

NORTHERN HEMISPHERE - winter/cooler temp from oct-feb. SOUTHERN exp summer/higher temp

IN NH, air cools n sinks, forming an area of higher pressure over central asia

IN SH, air warms up and rises, forming an area of lower pressure over australia

air thus moves from central asia towards australia, as the wind travels to their right due to the CORIOLIS effect, forms NE monsoon exp by countries like SG

southwest monsoon

from june to sept

in summer, air over central asia is warm, creating an area of low pressure.

in winter, the air over australia is cold, creating an area of high temperature,

air moves from aus to central asia (high p to low p)

when the winds cross into NH, they are deflected to the right forming southwest monsoon exp by SG

‘Monsoon winds bring the most variations in wind direction.’ How far do you agree with the statement? Support your answer with evidence.

I agree to a large extent that monsoon winds bring the most variations in wind direction. 

The Northeast monsoon occurs from October to February. The Northern Hemisphere experiences winter and cooler temperatures and the Southern Hemisphere experiences summer and higher temperatures.

In the Northern Hemisphere, air cools and sinks, forming and area of higher pressure over Central Asia. In the Southern Hemisphere, air warms up and rises, forming and area of lower pressure over Australia. Air moves from Central Asia to Australia. As winds travel towards India, they are deflected to the right due to the Coriolis effect, forming the Northeast monsoon which is experienced by countries such as India, Singapore and Malaysia.

The Northeast Monsoon is dry and cool as little moisture is picked up from Central Asia, thus India experiences little rain. As the winds blow over the South China Sea, the winds pick up moisture in the form of water vapour, which brings heavy rain to areas such as Singapore.

When the winds cross over into the Southern Hemisphere, they deflect to the left, and continue to pick up moisture over the Indian Ocean, which brings rain to countries like Indonesia and Australia.

Land breezes happen at night when both land and sea lose heat to the environment through longwave radiation. The sea loses heat slowly, hence the air above the sea is warmer. The land loses heat quickly, hence the air above the land is cooler. The warmer air above the sea is less dense and rises, creating a void. An area of lower pressure develops over the sea. The cooler air above the land is denser and sinks. An area of higher pressure develops over the land. Air moves from area of higher pressure over the land to an area of lower pressure over the sea, forming land breeze. 
In conclusion, monsoon winds bring variation in wind direction on a global scale across the equator and across the hemisphere and eventually get deflected due to Coriolis effect whereas land and sea breeze only brings variation in wind direction locally on a smaller scale across land either onto landmasses or water bodies.

Latitude

-horizontal lines

-distance north or south of the equator

-parallels

-concentric circles

-different lengths

Longitude

-vertical lines

-distance east or west of prime meridian

-meridians

-pole to pole

-converse at poles

-same length

23.5º

tilt of earth

23.5º N

Tropic of Cancer

23.5º S

Tropic of Capricorn

Remote Sensing

Collecting data from a distance

Passive Systems

-type of remote sensing

-measure natural energy

Active systems

-type of remote sensing

-direct an energy beam and measure amount returned

Geographic information systems (GIS)

A set of computer tools used to capture, store, transform, analyze, and display geographic data layers

Layers of atmosphere

formed with different temperature, pressure, and composition

Pause

separates the layers of atmosphere

Atmospheric profile

based on density of air molecules and pressure of atmosphere

Troposphere

The lowest layer of Earth's atmosphere

gases in this layer are mixing

contains 70% of atmospheric mass

Stratospheric

gases here are layered by weight

jets fly through this layer

includes o-zone layer

in between troposphere and mesosphere

mesosphere

in this layer temperature is increasing with height

in between the stratosphere and thermosphere

thermosphere

in this layer the temperature can become very hot as gas molecules capture heat from the sun, in between space and the mesosphere

the o-zone

layer within the stratosphere that traps harmful UV-rays, which makes the layer itself very hot

made up of 03

kinetic energy

energy due to motion

can lead to heat

potential energy

stored energy

latent energy

form of energy transferred by changes in phases of matter

Convection

type of energy transfer

direct contact

advection

type of energy transfer

transferred by moving objects horizontally

radiation

type of energy transfer

transferred through electromagnetic waves

conduction

type of energy transfer

transferred through vertical motion

Electromagnetic radiation (EMR)

a form of energy that exhibits wavelike behavior as it travels through space

Stephen-Boltzman law

Amount of EMR increases as Temperature increases

Wien's Law

The higher the temperature of a body the shorter the wavelength of it's maximum radiation. (hotter = shorter wavelength)