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UNIT 2
Chapter 1: Inquiring about Weather
Unit 2: Weather Dynamics
Chapter 1: Earth’s Energy Budget
Science 10
Mrs. Purba
UNIT 2 Chapter 1: Inquiring about Weather
Section 1.1
Earth’s Energy Budget
Explain why visible light is represented by a rainbow of colours in the
figure below.
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Solar energy is energy generated by the Sun.
It consists of 7 types of electromagnetic waves.
UNIT 2 Chapter 1: Inquiring about Weather
Section 1.1
Earth’s Energy Budget
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Solar energy travels to Earth by a process called radiation− thermal
energy transfer in which atoms or molecules give off energy as
electromagnetic waves when they interact with matter such as air,
water, or soil.
Solar energy is reflected, absorbed, or emitted (given off) by matter
as it travels through the biosphere.
The various wavelengths of solar energy are affected differently when
they reach Earth.
Earth maintains an energy and temperature balance because
approximately the same amount of energy enters and leaves Earth’s
atmosphere.
UNIT 2 Chapter 1: Inquiring about Weather
Incoming and Outgoing Radiation
About 49% of the
solar energy that
enters Earth’s
atmosphere is
absorbed by the
land.
About 42% is
absorbed, reflected,
and scattered by
clouds, gases, and
aerosols in the
atmosphere.
About 9% is
reflected by Earth’s
surface.
How can a cloud absorb thermal energy?
Section 1.1
UNIT 2 Chapter 1: Inquiring about Weather
Section 1.1
Factors Affecting Absorption of Energy
Both the colour and type of a substance affect its ability to absorb
energy.
• Dark colours absorb energy.
• Light colours reflect energy.
A substance’s albedo is the amount of energy its surface can reflect.
Give an example of a substance that has a high albedo and a
substance that has a low albedo.
UNIT 2 Chapter 1: Inquiring about Weather
Section 1.1
Factors Affecting Absorption of Energy
Different substances absorb energy at different rates.
• The property of a substance that involves how a substance
absorbs and releases energy (and how quickly) is called its
specific heat capacity.
• Water has a high specific heat capacity.
• Water heats up and cools off more slowly than land does. Both
water and land heat up and cool off more slowly than air does.
Water is a heat sink.
UNIT 2 Chapter 1: Inquiring about Weather
Section 1.1
Keeping in the Heat
Why doesn’t thermal energy radiate into space at night?
• The greenhouse gases act as a heat sink. They absorb thermal
energy and radiate the energy in all directions.
• These gases cause the troposphere—where weather occurs—to
retain more heat than it would if these gases were not present.
What can occur
when the atmosphere
contains more
greenhouse gases than
normal?
UNIT 2 Chapter 1: Inquiring about Weather
Section 1.1
Thermal Energy Transfer
by Conduction, Convection, and Radiation
Thermal energy is transferred from a warmer object to a cooler object,
and it is transferred in three ways.
1. Radiation is the transfer of thermal energy by electro-magnetic
waves.
2. Conduction is the transfer of thermal energy between two objects or
substances that are in direct contact.
3. Convection is the transfer of thermal energy by the movement of
heated material (liquids or gases)
from one place to another.
UNIT 2 Chapter 1: Inquiring about Weather
Section 1.1
Thermal Energy Transfer
by Conduction, Convection, and Radiation
Explain in your own words how thermal energy is transferred in the
atmosphere by conduction, convection, and radiation.
UNIT 2 Chapter 1: Inquiring about Weather
Section 1.1
Atmospheric Pressure
• The pressure exerted by the mass of air above any point on
Earth’s surface due to the weight of the air.
• The SI unit for atmospheric pressure is the Pascal (Pa) or
kiloPascal (kPa)
• Pascals are used to measure the force per unit area. One Pascal
has a force of one Newton per square metre.
UNIT 2 Chapter 1: Inquiring about Weather
Section 1.1
Temperature & Atmospheric Pressure
• As particles of air are heated, they
move more quickly and move farther
apart, because their kinetic energy has
increased.
• As a result, warm air is less dense
than cold air because the gas particles
that make up the air are farther apart.
• When warm air pushes into an area of
cold air near the ground, the
atmospheric pressure in that location
decreases.
• When cold air pushes into a region of
warm air, the atmospheric pressure in
that location increases.
UNIT 2 Chapter 1: Inquiring about Weather
Section 1.1
Humidity & Atmospheric Pressure
• Humidity is a measurement that describes the amount of water
vapour in air.
• The more water vapour in the atmosphere, the lighter the air is.
• Humid, or “wet,” air exerts less atmospheric pressure than dry air.
UNIT 2 Chapter 1: Inquiring about Weather
Section 1.1
Atmospheric Pressure
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At sea level, the atmospheric pressure is about 101.3 kPa.
As altitude increases, atmospheric pressure decreases.
As altitude increases, temperature decreases.
As altitude increases, the density of the atmosphere also
decreases.
• How would the changes in
altitude, temperature, density,
and atmospheric pressure affect
a mountain climber on the peak
of Mount Everest?
UNIT 2 Chapter 1: Inquiring about Weather
Section 1.1
Atmospheric Pressure
Meteorologists—scientists who study weather– use atmospheric
pressure readings to predict changes in the weather.
• A decrease in atmospheric pressure suggests that warm, humid air
is approaching and that the temperature will increase.
• An increase in atmospheric pressure suggests that cool, dry
weather is approaching.