Weather & Climate

The Key Questions:► What is the difference between Weather and

Climate and how do we measure it accurately?

► What are the factors that we need to consider when measuring the various elements of weather?

► What is happening to the Earth’s climate?

► How will climate change affect our environment and way of life?

► What can we do to cope? What measures have been put in place to slow down these changes?

“Climate is what you expect, weather is what

you get.”Mark Twain

Research!

What is the temperature going to be like in the following cities over the next 3 days?

CityDay 1

(highest | lowest)

Day 2(highest | lowest)

Day 3(highest | lowest)

Day 4(highest | lowest)

Tokyo

Jakarta

Sydney

Analyze!

Why is it important to know the highest and lowest temperature readings, and not just the average?

Is the data reliable? Do you think the temperature readings be exactly as predicted?

What other data would you want to look at?

WeatherRefers to the conditions of the atmosphere at a specific place over a relatively short period of time.

Hard to predict exactly (but not impossible) as it changes so fast and is dependent on different elements.

Elements of Weather:

Temperature

• Latitude• Altitude• Continental &

Maritime Effect

• Cloud Cover

Relative Humidity &

Rainfall

• Relative Humidity

• Convectional Rain

• Relief Rain

Pressure & Winds

• Air pressure• Land & Sea

Breezes• Monsoon

Winds

Discuss!

If you were a scientist and you wanted to prove that the Earth is getting warmer, which of the following set of data would you use?

Set A

Weekly Weather Forecast

Set B

ClimateRefers to the atmospheric conditions of a specific place over a considerable period of time, usually 30 years.

Data for climate can take years to collect and accurately construct.

Climate VS. Weather

Differences:

► Climate is used to study LONG term changes in the atmosphere.

► Weather is used to study SHORT term changes in the atmosphere.

Similarities

► Climate is essentially weather data gathered over a looooong period of time.

Elements of Weather:

Temperature

• Latitude• Altitude• Continental &

Maritime Effect

• Cloud Cover

Relative Humidity &

Rainfall

• Relative Humidity

• Convectional Rain

• Relief Rain

Pressure & Winds

• Air pressure• Land & Sea

Breezes• Monsoon

Winds

Temperature Refers to the degree of hotness or

coldness

Determined by energy from the sun

High temperatures are defined as anything >20°C and low temperatures as anything <10°C

A small temperature RANGE would be <10°C while a large temperature range would be >15°C

How do meteorologists calculate these readings?

Mix-n-match

Mean Daily Temperature

• • Sum of mean monthly temp in

a year12

Diurnal Temperature Range

• • Max. mean monthly

temperature – min. mean monthly temperature

Mean Monthly Temperature

• • Sum of mean daily temp in a

monthNo. of days in that month

Mean Annual Temperature

• • Sum of hourly temperatures

24

Annual Temperature Range

• • Max. daily temperature – min.

daily temperature

What are the factors affecting the temperature

of a place?

Factors affecting Temperature

► Latitude

► Altitude

► Distance from the sea

► Cloud cover

Latitude

► Refers to: the distance of any point on the Earth

measured north or south from the Equator.

imaginary horizontal lines that circle the Earth and measured in degrees.

► Equator: 0°, North Pole: 90°N,

South Pole: 90°S

► Singapore: 1°22’N (1°, 22 mins NORTH of the Equator) 1 min of latitude is 1.853 km

How it is measured:

Latitude

► Determines the mean annual temperature and seasonal variations

► In general: Lower latitudes (i.e. nearer to

equator), high temperature

► Due to Tilt of the Earth’s Axis Angle of Incidence

Angle of 23.5°

May to July

Nov to Jan

Latitude: Angle of Incidence

► What is the angle of incidence?

► What is the highest/lowest angle one can go?

► What effect does it have on temperature if it is higher/lower?

Latitude: Angle of Incidence

► Nearer to the Equator, the Sun’s rays strike the Earth’s surface more perpendicularly (90°).

► The high angle of incidence causes the solar radiation to be concentrated over a smaller area, causing more intense heat.

► Hence the equatorial region experiences higher annual mean temperatures

Latitude: Angle of Incidence

► At the higher latitudes, the Sun’s rays strike the Earth’s surface at smaller angles.

► This causes the solar radiation to be spread over a larger area.

► Hence the higher latitudes experiences lower annual mean temperatures

Self-Assessment

► “Weather and climate are the same.” True/False? Explain.

► “Weather and climate are related.” True/False? Explain.

► What happens to the Angle of Incidence as latitude increases?

► If the Earth was square instead of round, would there still be seasons?

► What would happen to the average temperatures around the world if the Earth was tilted 90°

Think Quest:

Both Tampa, FL and Kathmandu, Nepal are located 28ºN

Think Quest:

Think Quest:

Predict the temperature data of Kathmandu

Think Quest:

Think Quest:

Kathmandu:Highest: 25ºCLowest: 2ºC

Tampa:Highest: 33ºCLowest: 11ºC

Altitude

Altitude

► Refers to the height of a place in relation to the sea level.

► Relationship to temperature: Temperatures decrease with an

increase in altitude

Altitude

Video Learning:

Click on pic for link

Video Learning:

Altitude: The Basics

► Our Earth’s atmosphere is warmed by LONG and SHORT wave radiation. Shortwave: heat from the sun Longwave: heat from the Earth

Altitude: The Basics

► Heat from the sun enters the earth’s surface as shortwave radiation.

► Most of it gets absorbed, warming the Earth. Others gets reflected back to space by the clouds and atmosphere.

► The warmed Earth surface now emits heat of its own. This is known as longwave radiation.

How Altitude Affects Temp.

► The Earth’s atmosphere consists of gases and molecules which absorbs heat emitted by longwave radiation.

► At places near sea level, there is a higher concentration of gases due to the forces of gravity.

► Hence, more heat is being absorbed at lower latitudes, which is why temperatures are higher.

► At higher latitudes, the air is less dense and its ability to absorb heat decreases, resulting in lower temperatures.

Think Quest answer:

Tampa is located at a lower altitude (14.6m) than Kathmandu (1,400m)

Recap

► Latitude Tilt of the Earth Angle of incidence

► Altitude Shortwave radiation Longwave radiation Air pressure

Self-Assessment

► Explain why it is harder to breath further up a mountain.

► “If every country had the same altitude, the average temperature in each country would be the same.” Agree/Disagree? Explain.

Practice:PitStop 2Q1 and 2

Think Quest

Maritime and Continental Effect

Maritime & Continental Effect

Remember!

► Land heats up very quickly and loses heat quickly.

► Large water bodies take a longer time to heat up, but once heated up will retain heat longer (i.e. lose heat slowly)

Lets do some research!

► Head to: http://www.wunderground.com/wundermap and search for Los Angeles, California

► Compare and contrast the difference between the temperature readings Along the coastlines Areas 50km from the coastline

► Which area has higher/lower readings

Maritime Effect

► Refers to the effect that large ocean bodies have on the climate of an area.

► During summer, air over land heats up quickly but air over the seas remain cool.

► Winds blowing from the coast thus bring in cooler air, lowering the temperature along the coast, leading to cooler summers.

Maritime Effect

► During winter, the air over the sea loses heat more slowly, thus remaining warmer than the air over land.

► The warmer air blowing in from the seas thus helps to raise the temperature of the coastal areas, leading to warmer winters.

► Hence coastal areas have smaller temperature ranges.

Continental Effect

► Inland areas are not influenced by the maritime effects of the sea.

► During summer, the air over the land heats up quickly leading to warmer summers.

► During winter the air over the land loses heats quickly leading to colder winters.

► Hence inland areas have larger temperature ranges.

Think Quest

The Kalahari Desert

Daytime: > 40°CAt night: < 0°C

Question:

Why are temperatures in the day so high and yet, come nightfall, the temperature can plunge so rapidly?

Cloud Cover

Cloud Cover

During the DAY,

Temperatures are lower during cloudy days.

Why?

Because clouds reflect part of the incoming solar radiation back to outer space.

During the day…

Cloud Cover

At NIGHT,

Temperatures are higher during cloudy nights.

Why?

Because clouds absorbs more heat radiating from the Earth’s surface and prevents it from escaping to space.

At night…

Homework:PitStop 2Q3 to 6