Download Introduction To Weather Dynamics

Introduction To
Weather Dynamics
Introduction to Weather - Video
What you will learn…
In this unit, you will…
•Describe Earth’s energy budget
•Explain how energy is transferred between and
among land, air and water
•Describe weather-related properties of the
atmosphere such as pressure and humidity
•Explain how areas of high and low pressure
move air and energy around the globe
Meteorology
The study of
the Earth’s
atmosphere
and weather
systems.
Weather
(page 10)
The day to day
changes in the
atmosphere
at a particular
location
on Earth.
Climate
A
widespread,
long-lasting and
recurring
conditions of the
atmosphere.
• Weather – What is it?
Components of Weather
(see Table 1.1, page 11)
Temperature
Coolness or warmth of an object
(average of kinetic energy – oC)
Precipitation
Any form of water that falls to Earth
from atmosphere (mm or cm)
Atmospheric Pressure
The force of the atmosphere per
square meter of surface below it
(kPa)
Humidity
The amount of water vapor in the
air (%)
Wind Speed & Direction
How quickly the air moves and its
direction (km/h; NSEW bearings)
Sky Cover
The portion of sky that is covered
by clouds
• Sheet to complete: Part A
• To do: p. 4, #4 & 6
Earth’s Energy Budget
(page 13)
Types of Energy Transfer Radiation
• Energy is transmitted as photons
(electromagnetic radiation)
• Think: The Sun!
Solar Radiation
• Solar constant is defined as the amount
of radiant energy that hits one square
meter of the Earth’s outer atmosphere
every second (1362 J/s/m2)
• Unit of energy → Joule (J)
• See Figure 1.4, page 14
• Greenhouse Effect – the warming of
Earth as a result of greenhouse gases
(CO2, water), which trap some of the
energy that would otherwise leave Earth
Terrestrial Radiation
• Earth would constantly increase in
temperature if it did not radiate energy
back to space.
• It would take approximately 25 years for
the oceans to boil if no energy was emitted
back to space
• Terrestrial Radiation is composed primarily
of infrared photons (light)
Incoming and Outgoing Radiation
• About 49% of the solar energy that enters
Earth’s atmosphere is absorbed by the
land and ocean.
• About 42% is absorbed, reflected, and
scattered by clouds, gases, and aerosols
in the atmosphere.
• About 9 percent is reflected by Earth’s
surface.
• Figure 1.4
Solar Radiation Arriving at Earth’s
Surface (see Figure 1.4, page 14)
• Sheet to complete – Part B
Factors Affecting Absorption of
Energy
• 1. The colour of a surface:
– Which one reflects more light?
• Snow or a farmer’s field?
• Albedo - the reflectivity of a surface
– Field in the summer – 20%
– Field covered with snow – 70 or 80%
Factors Affecting Absorption of
Energy
• 2. The nature of a substance: Different
substances absorb energy at different rates.
– Which one will warm up more quickly? Water or
sand?
• The Specific Heat Capacity of a substance
determines how much and how quickly it
absorbs and releases energy.
• Water has a much higher specific heat capacity
than land and air do.
Specific Heat Capacity
Substance
Specific Heat Capacity at 25oC
(J/kg/oC)
Water
4186
Air
1020
Iron
444
Copper
385
Sand
290
Gold
129
Heat Sinks
• Because the specific heat capacity of
water is higher than that of land, water is
considered to be a better heat sink.
• Heat Sink: any substance that can
absorb and retain energy without changing
state.
Water is a good heat sink
• Because there is so much water on Earth,
and water is such a good heat sink, water
has a great influence on weather.
• Is it colder in the winter in Saskatoon or
Halifax?
• Is it colder in the summer in Saskatoon or
Halifax?
Figure 1.5
• The energy transformations that
happen between the time solar
radiation is absorbed and the time
it is re-emitted are what drive
weather systems.
• Practice sheet – Part C
• Questions – p. 15, 1-4
– Answers
Thermal Energy Transfer
• Thermal Energy – Energy created by the
movement of particles in a substance.
• Heat: Thermal energy that is transferred
from one object to another
• There are three types of heat transfer…
– Conduction
– Convection
– Radiation
Types of Energy Transfer Conduction
• Requires contact between atoms; more
energetic atoms collide with more
energetic atoms and energy is transferred
(solids with solids)
• Example: Warming a pot on a stove
Types of Energy Transfer Convection
• In a gas or liquid, atoms are free to move
and as they warm they become less dense
and rise. Atoms that are cold and denser
will then descend and create a convection
current.
– (liquids/gas)
Types of Energy Transfer Radiation
• Energy is transmitted as photons
(electromagnetic radiation)
• Think: The Sun!
• Definitions – Conduction, Convection and
Radiation
• Video – Radiation , Conduction and
Convection
• Draw – p. 17, fig. 1.7
Atmospheric Pressure
• Atmospheric Pressure – the pressure
exerted by air on its surroundings due to
the weight of the air
• Measured in kilopascals (kPa)
• At sea level, the atmospheric pressure is
101.3 kPa (or 1 kg/cm3)
Three factors that can reduce
atmospheric pressure:
• Altitude – The higher you go, the pressure
decreases
• Temperature – When warm air pushes into a
cold air mass, pressure decreases. When cold
air pushes into a region of warm air, the
atmospheric pressure in that location increases.
• Humidity – The more water vapour in the
atmosphere, the more the air is light (so more
humidity = less pressure)
• Video – Atmospheric Pressure
Layers of the Atmosphere
See Figure 1.8,
page 19
Layers
the Atmosphere
Atmosphere
Layers of
of the
• Troposphere
– All water vapour is present here
– All weather occurs here
– From surface to ~10km
– Temperature ranges from -50°C to 50°C
• Stratosphere
– Ozone is present here
– From 10km-50km
– Temperature ranges -50°C to -30°C
Layers of the Atmosphere
• Mesosphere
–
–
–
–
Meteorites burn up here
Some ions are present here
From 50km to 90km
Temperature ranges from -30°C to -90°C
• Thermosphere
–
–
–
–
Aurora present
Some ions are present here
From 90km to 180km (space)
Temperature ranges from -90°C to over 200°C
Layers of the Atmosphere
• Video – Layers of the atmosphere
• To do:
– Finish worksheet:
• Answers