Section 2-3: Heat
Transfer, The Water
Cycle, and Wind
Lesson Objective
 By the end of this lesson, you should be able to:

a.) Describe the main processes of the water cycle

b.) Explain how weather is related to water cycle processes

c.) Explain how energy from the sun drives wind and water currents
 d.) Explain how energy from the sun is distributed around the globe
Questions To Ask Yourself
I.) How is the sun’s energy transferred around the globe?
II.) What is the water cycle and why is it important?
III.) How does the water cycle influence weather patterns?
IV.) How do winds form?
Vocabulary
 1.) Thermal Energy
11.) Ground Water
 2.) Conduction
12.) Transpiration
 3.) Convection
13.) Photosynthesis
 4.) Radiation
14.) Wind
 5.) Pressure Gradient Force
15.) High Pressure
 6.) Water Cycle
16.) Low Pressure
 7.) Evaporation
17.) Sea Breeze
 8.) Precipitation
18.) Land Breeze
 9.) Condensation
19.) Convection Currents
 10.) run-off
20.) Jet Stream
Video’s
 The Water Cycle:
 https://www.youtube.com/watch?v=al-do-HGuIk
 Heat Transfer:
 https://www.youtube.com/watch?v=lP40H9K5Ykk
 Wind Circulation
 https://www.youtube.com/watch?v=m6FpZCM5qaU
I.) How is the sun’s energy transferred around the globe?
*The Earth must maintain an Energy (or Heat) Balance!*
Earth gains energy from the
Sun (or warms) by Incoming
Shortwave Radiation. Thermal
energy is produced by
incoming shortwave radiation
Earth
Sun
Earth emits energy to
space (or cools) by
Outgoing Longwave
Radiation
m
.
I.) How is the sun’s energy transferred around the globe?
Heat Transfer within the Earth’s Atmosphere
I.) How is the sun’s energy transferred around the globe?
The Role of Mid-Latitude Synoptic Systems
Maintaining the Global Heat Balance
• The Earth cool everywhere via radiation
(the tropics, midlatitudes, and poles)
• Due to the Earth’s small tilt with respect
to its axis of rotation, the tropics
received much more energy (heat)
from the Sun than the polar regions
• Thus, over time, a strong north-south
gradient in temperature develops
Nature hates strong gradients!!!
The role of mid-latitude synoptic weather
systems is to remove this gradient by
transporting (or advecting) warm air
poleward and cold air equatorward
M.D. Eastin
I.) How is the sun’s energy transferred around the globe?
- Energy Transfer in weather occurs on a global scale, and energy from the sun
has a huge impact on water and wind currents on Earth.
- One way the sun affects weather is through wind patterns.
- The shortwave radiation from the sun warms the ground, which in turn heats
the air above it.
- However, not all of the Earth’s surfaces absorb or radiate heat energy at the
same rate. Land heats up and cools down more quickly than water does. This
is due to sensible heating of water.
- These temperature differences also affect the temperature of the air, causing
weather patterns such as sea breezes and land breezes.
- **The uneven heating of Earth by the Sun is therefore responsible for wind
patterns, which in turn have a direct impact on weather.**
I.) How is the sun’s energy transferred around the globe?
Conduction: Direct heat transfer of heat energy from one substance to another
(solids).
Example: The sun warms Planet Earth. The surface of the Earth acts as a conductor
as the shortwave radiation heats up the ground.
I.) How is the sun’s energy transferred around the globe?
Convection: Transfer of heat energy in a fluid, gas or liquid.
Example: Wind currents develop within the Earth’s Atmosphere due to
temperature and pressure differences. In order for heat to be
transferred to other regions, it must be transferred horizontally by the
wind. The horizontal transfer of heat by the wind is called advection.
I.) How is the sun’s energy transferred around the globe?
Radiation: the transfer of heat energy through empty space
Example: Radiation from the sun hits Earth in the form of shortwave radiation.
We feel the radiation (heat) from the sun. *Think of the Sun’s
radiation*
I.) How is the sun’s energy transferred around the globe?
Wind: Air in natural motion due to different temperature or pressure
differences within the Earth’s atmosphere. Advection of the wind moves
warm air over cool air, or cool air below warm air. This type of air
movement can produce convective currents within the Earth’s
atmosphere. This is also due to high/low pressure within the
atmosphere.
I.) How is the sun’s energy transferred around the globe?
The Role of Mid-Latitude Synoptic Systems
Maintaining the Global Heat Balance
• The gradients are continuously removed through the interaction of upper-level waves
in the jet stream with large-scale high and low pressure systems near the
surface
II.) What is the water (hydrological) cycle, and why is it
important?
The Water Cycle: describes the continuous movement of water on, above and
below the surface of the Earth.
a.) Evaporation: The changing of a liquid into a gas, often under the
influence of heat (Evaporation from verga! ).
b.) Precipitation: is any product of the condensation of atmospheric
water vapor that falls under gravity (rain, snow, sleet,
or hail that falls to the ground).
c.) Condensation: is the change of the physical state of matter from gas
phase into liquid phase (Clouds forming from water
vapor.
d.) Surface Run-Off: is the flow of water that occurs when excess water
from rain, melt water, or other sources flows over the
earth's surface. This might occur because soil is
saturated to full capacity, or because rain arrives
more quickly than soil can absorb it.
e.) Ground Water: is the water located beneath the earth's surface in soil pore
spaces and in the fractures of rock formations.
II.) What is the water (hydrological) cycle, and why is it
Important?
f.) Transpiration: is the process of water movement through a plant and its
evaporation from aerial parts, such as from leaves but also from stems and
flowers.
g.) Photosynthesis: the process by which green plants and some other organisms
use sunlight to synthesize foods from carbon dioxide and water.
III.) How does the water cycle influence weather patterns?
-
The sun’s energy affects the movement of water on Earth. This process is known as the water
cycle, which is composed of three main phases: evaporation, condensation, and precipitation.
-
The sun’s heat causes water on Earth’s surface to change from a liquid to a gas form. The
evaporated water then rises into the air. The higher the air mass gets, the cooler the air
temperature becomes.
-
Eventually, the water vapor begins to condense into tiny droplets that form clouds in the sky.
When the liquid droplets become heavy enough (fall through the updraft),they fall back to
Earth as liquid or solid particles.
-
The water cycle helps to move the water around the Earth.
-
The movement of water through the water cycle causes weather patterns such as cloud
formation and precipitation
- Humidity is the measure of the amount of water in the air. The dew point is the point at which
the temperature of the air and the humidity allow the formation of water droplets. When
precipitation occurs, the humidity is 100% and the dew point has been reached
III.) How Does the Water Cycle Influence Weather Patterns?
- The water cycle is a critical element in weather patterns. Large bodies of water,
such as oceans and lakes, feed the atmosphere with evaporated water. As the
water vapor rises, clouds form and become heavy with precipitation.
- Air currents move these clouds over land, where they eventually drop the water
as precipitation. Areas like the Pacific Northwest and areas around the Great
Lakes receive a lot of precipitation due to the water cycle.
Homework 1 “The Water Cycle” and Processes
Draw “The Water Cycle” and the processes that go along with the cycle.
Example: Precipitation, Condensation, Evaporation, Convection, infiltration,
percolation, surface runoff, groundwater storage, transpiration, and
photosynthesis.
IV.) How do Winds Form?
- Warm air is less dense than cooler air (Low Pressure). When
the sun’s energy warms air, the warm air rises and the air
pressure drops.
- Cooler air is denser and therefore sinks (High Pressure). Air
moves (advection) across Earth’s surface between areas of
warm rising air and cool sinking air. Moving air is wind.
- ***Wind is caused by differences in temperature and
density fluxuations within the Earth’s atmosphere!!!!***
IV.) How do Winds Form?
Forces Driving Synoptic-Scale Air Motions
1.) Pressure Gradient Force: The change in pressure
measured across a given surface.
- Pressure is a force per unit area
- Air pressure is the weight (mass) of the atmosphere
above a given location
- Air pressure is a function of temperature and density
- Air pressure decreases with altitude at a decreasing rate
- Air always tries to flow down the pressure gradient
from regions of high pressure toward regions of
lower pressure → the pressure gradient force
- The pressure gradient force is directly proportional
to the magnitude of the gradient.
IV.) How do Winds Form?
Forces Driving Synoptic-Scale Air Motions
Horizontal PGF – Coriolis Force
Horizontal PGF:
• Acts to accelerate air from regions of high
pressure toward regions of low pressure
2.) Coriolis Force:
• Apparent force (Earth is rotating reference frame)
• Always acts to accelerate air 90° to the right
of the wind vector in the northern hemisphere
• Magnitude is proportional to the wind speed
Flow down the
pressure gradient
Video: The Coriolis Effect
https://www.youtube.com/watch?v=i2mec3vgeaI
IV.) How do Winds Form?
Forces Driving Synoptic-Scale Air Motions
Cyclonic Flow
• Counter-clockwise flow (N Hemisphere)
• Occurs in association with low pressure
systems (called “cyclones”)
Anticyclonic Flow
• Clockwise flow (N Hemisphere)
• Occurs in association with high pressure
systems (called “anticyclones”)
m.d. eastin
Jet Streams and Jet Streaks
The Midlatitude Jet Stream:
• 100-400 miles wide
• 500-3000 miles long (non-continuous around the globe)
• Winds speeds range 50-200 knots
• Located between 200-400 mb (altitude of largest N-S pressure gradient)
• Westerly flow in northern hemisphere (Why?)
• Faster moving pockets of air embedded within the Jet Stream
 Moves/Bends/Buckles from day to day in response to large-scale heating / cooling
 Play important roles in steering and intensifying/weakening surface highs and lows
North Pole
Equator
Video: Air Currents
https://www.youtube.com/watch?v=m6FpZCM5qaU
Wind Currents: air moving from an area of high pressure to an area of low pressure.
Trade Winds: a wind blowing steadily toward the equator from the northeast in the
northern hemisphere or the southeast in the southern hemisphere, especially at sea.
Two belts of trade winds encircle the earth, blowing from the tropical high-pressure belts
to the low-pressure zone at the equator.
Prevailing Westerlies: are prevailing winds from the west toward the east in the
middle latitudes between 30 and 60 degrees latitude. They originate from the highpressure areas in the horse latitudes and tend towards the poles and steer extratropical
cyclones in this general manner.
Polar Easterlies: are the dry, cold prevailing winds that blow from the high-pressure
areas of the polar highs at the north and south poles towards low-pressure areas within
the Westerlies at high latitudes.
Doldrums: an equatorial region of the Atlantic Ocean with calms, sudden storms, and
light unpredictable winds.
Horse Latitudes: a belt of calm air and sea occurring in both the northern and southern
hemispheres between the trade winds and the westerlies.
Homework #2 Global Wind Currents
1.) I want everyone to draw out a globe
2.) draw inside the globe the polar region (60-90 degrees) to the equator
(0-30 degrees) and the mid latitudes (30-60 degrees)
3.) draw inside the globe the doldrums, trade winds, prevailing
westerlies, and polar easterlies (DRAW THE WIND DIRECTIONS).
4.) Draw an example of a convective current on the globe.
Write out the
Definitions for extra
Credit (10 points)
Essential Standards: Understand how the cycling of matter in and out of the
Atmosphere relates to Earth’s atmosphere , weather, and climate and the
Effects of the atmosphere on humans.
Clarifying Objectives: 7.E.1.2 Explain how the cycling of matter in and out of the
Atmosphere and atmospheric conditions relate to weather patterns on Earth.
7.E.1.5 Explain the influence of convection, global winds, and the jet stream on weather and climate
conditions.
Essential Questions: 7.E.1.2 How do weather patterns exist in the Earth’s Atmosphere? How does
the water cycle influence and drive weather conditions on Earth? What factors influence your daily
weather variations? Why is the study of meteorology important? 7.E.1 What is the relationship
between energy transfer and the Earth’s weather? How do heating systems and wind currents
within the atmosphere influence weather conditions? How does gravity impact the jet stream?
Learning Targets: 7.E.1.2 I can explain the significance of the water cycle and how it relates to
weather patterns on Earth. 7.E.1.5 I can explain the influence of radiation, convection, and
conduction in relation to the atmosphere. I can explain the influence of convective currents, global
winds, and the jet stream on weather conditions.
Learning Outcomes: 7.E.1.2 I will model and illustrate the water cycle. I will explain the different
phases of the water cycle. 7.E.1.5 I will identify the differences in conduction, convection, and
radiation within the Earth’s atmosphere. I will explain why and how winds curve due to the coriolis
force.