weather when is the earth closest to the sun?€¦ · sun directly on tropic of cancer (23.5° n)...

When is the Earth closest to the sun?

__________________________________________________________________________________________________________________________.

WEATHER

Discuss with your table partner:

Why is sunlight at the equator more intense? Compare a flashlight shining directly on a surface (90° angle) vs. at an acute angle. Why does the intensity change?

Review of Weather Basics

Indirect light is _______ intense than direct light, since the same amount of light is ______________________. The equator receives the more direct light throughout

the year.

Seasons The seasons are caused by the tilt of the Earth on its

axis by 23.5°.

Tropics (Cancer/Capricorn) = 23.5° (N/S) Artic circle = ___________________

Summer solstice (~ June 21st) for northern hemisphere Northern pole tilted towards the sun Sun directly on Tropic of Cancer (23.5° N) Longest day in Northern Hemisphere

Autumnal Equinox (~ September 22nd) Tilt of axis parallel to sun (not towards or away) Sun directly on Equator Equal day and night at all latitudes

Winter solstice (~ December 22nd) Sun directly on Tropic of Capricorn (23.5 ° S) Longest day in the Southern Hemisphere

Vernal (Spring) Equinox (~ March 21st) Sun directly on Equator Equal day and night at all latitudes

Location Position of sun at midday on June 21st

• Directly overhead • South • North

Length of Day • ≈ 12 hours • Much greater • Greater • Much less • Less

Dhaka, Bangladesh (23.5°N) Kampala, Uganda (O°) Cusco, Peru (13.5 °S) Tierra del Fuego, Arg. (55 °S)

Discuss with your table partner:

Review the orbit of the Earth around the sun and determine how the tilt of the Earth affects sun position and length of day throughout the year. We will in the charts on this slide together and then work with your table partner on the following slide.

Location Position of sun at midday on December 22nd

• Directly overhead • South • North

Length of Day • ≈ 12 hours • Much greater • Greater • Much less • Less

Dhaka, Bangladesh (23.5°N) Kampala, Uganda (O°) Cusco, Peru (13.5 °S) Tierra del Fuego, Arg. (55 °S)

Location Position of sun at midday on September 22nd

• Directly overhead • South • North

Length of Day • ≈ 12 hours • Much greater • Greater • Much less • Less

Dhaka, Bangladesh (23.5°N) Kampala, Uganda (O°) Cusco, Peru (13.5 °S) Tierra del Fuego, Arg. (55 °S)

http://www.timeanddate.com/worldclock/sunrise.html

Tilted towards the sun

Tilt is parallel to the sun

Tilted away from the sun

Passive solar design can take into account different angles of sun.

3 Types of Heat Transfer

Conduction= Transfer of heat energy due to ________________ (particles collide)

Radiation= Energy is transferred through electromagnetic radiation (infrared rays)

Convection= Movement within fluid (_________ _______) as hotter, _______________ fluid rises.

Discuss with your table partner:

• Is the relationship direct or inverse? • Relate what you know about how air changes as it is

heated to why increased temperature has this effect on the amount of water vapor the air can hold.

• Why does dew sometimes form overnight?

Study the graph to review the effect of temperature on the water vapor capacity of air.

The Effect of Temperature on Air’s Water Vapor Capacity

There is a __________ relationship between the temperature and the amount of water vapor air can hold. (_______water vapor capacity at increased temperature)

Because hot air is ___________, it has a ________ capacity to hold water vapor.

As air cools, it may be _____________ with water vapor and the ______________________________.

Discuss with your table partner:

Referring to the previous graph that shows the effect of temperature on the maximum water capacity of air, try to answer the questions on the following three slides.

The chart below shows that besides deserts, the tundra is one of the biomes with the lowest average annual precipitation. Explain why this is the case.

____________________________________________________________________________________________________________

Relative humidity is the amount of water vapor in the air compared to the maximum it can hold at that temperature and pressure. (Amount of H2O vapor/Maximum H2O vapor) x 100 If the air cools down without a change in the water content (no evaporation or precipitation), what happens to its relative humidity.

Discuss with your table partner:

Since air conditioners take in hot air and make it cooler, what happens to the water vapor capacity as the air temperature decreases? How must air conditioner design take into account this change?

_________________________________________________________________________________________________________

Since the hot air can hold more moisture (like the image on the left) that same amount of water has a ________ relative humidity. As air cools, its relative humidity ___________(if no change in water vapor).

Dew point = temperature at which condensation will form (for given temperature and humidity). Use the chart below to determine the dew point for air that:

___°F

___°F

• Is 75 °F and has 80% humidity

•Is 75 °F and has 100% humidity

Low pressure zones are caused by __________ at the earth’s surface.

Unlike air trapped in a closed system, air in the atmosphere ________________________________ _________________________________________.

Key Concepts

Low pressure at location of heating.

Low pressure zones can result in rain. • The rising column of air in a low pressure zone

_____________________________________. • As air cools it ___________________________. The key factor to remember is that low pressure air is ___________________________________.

High pressure is usually associated with _________.

Water’s Moderating Effect Water has a high specific heat, which means that it

takes ____________________ compared to most other substances.

(Because it takes extra energy to break the hydrogen bonds between water molecules).

So water changes its temperature _______________

_________________________________.

Wind

Winds arise from the uneven heating of the earth’s surface.

(Angle of light, differential heating of surface materials)

Creates difference in air pressure.

Wind Currents •Air moves outward ___________

_______________________________ •Differences in air pressure between

adjacent regions is what causes wind

H L

What the Barometer Means...

• Isobars = lines of equal pressure (usually measured in millibars -- mb)

• The more closely spaced the isobars, the more pressure changes with distance, and the ______ ________________________

H L High winds

Low Winds

Climate: Predominate weather patterns

Where are most rainforests and deserts located and why?

Most rainforests are located at the equator. • Since the equator receives the most direct light, it ______________________. • As air heats up it expands and rises. ( ______

pressure zone) • As the air rises, it ______ in the upper troposphere

and can no longer hold as much moisture. • This excess water vapor rains down on the tropics.

Most deserts are located at 30° N or 30° S.

● Air from the equator, moves towards the poles, cools and descends back towards the Earth at these latitudes. ● This air is dry (lost its moisture at the equator) • As it descends it _______________

__________________ . Relative humidity (% of moisture relative to its maximum) ________

Convection Cell

The pattern of a fluid rising and then sinking due to heating and cooling is called a convection cell.

This convection cell between the equator and 30° N or S is called a Hadley cell.

What direction does the Earth rotate?

View a globe rotating in this direction. What is the direction of the motion (clockwise vs. counterclockwise) when viewed from the Northern Hemisphere ?

What is the direction of the motion (clockwise vs. counterclockwise) when viewed from the Southern Hemisphere ?

Coriolis Effect

The apparent deflection of a moving object when viewed from a rotating frame of reference.

In the Northern Hemisphere, winds are deflected to the __________ .

In the Southern Hemisphere, winds are deflected to the __________.

Rotational Velocity The earth make one revolution on its axis per day. However, due to the different circumferences at different points on the earth, the rotational velocity varies from 1700 km/hr at the equator to zero at the poles.

Northern Hemisphere Circulation Patterns: Winds blow __________outward Winds blow _________from

high pressure areas in towards low pressure areas

H L

Ocean currents are generally clockwise in Northern Hemisphere

Hurricanes, which rotate towards low pressure zones, spin counterclockwise in Northern Hemisphere

Global Wind Patterns The convection cell patterns and the Coriolis

effect interact to create general global wind patterns.

Winds are named based on the direction of their ___________. Westerlies= ______________

Discuss with your table partner: • Review the Hadley Cell between the equator (O°) and

30° N. At the ground level does wind blow from North to South or South to North?

Hint: Where is the low pressure? Remember air moves towards a low pressure zone.

• Review which direction does the Coriolis Effect deflect wind in the Northern Hemisphere.

On the next slide, draw these directions as vector lines and combine them to determine the direction of the wind in this zone. Then repeat the process for the 30 S to equator zone and the 30 N to 60 N zones on the following slides.

30° N ______ Pressure

0° (equator) ____ Pressure

Direction of the Coriolis Force in the Northern Hemisphere: Be sure to draw the right or left arrow from the perspective of the North/South arrow.

_________

Due to ____________ ______________.

Due to __________ _________________.

30° S ______ Pressure

0° (equator) _____ Pressure

Direction of the Coriolis Force in the Southern Hemisphere _____________

Be sure to draw the right or left arrow from the perspective of the North/South arrow.

60° N ________ Pressure

30° N _______ Pressure

Direction of the Coriolis Force in the Northern Hemisphere _____________________

Be sure to draw the right or left arrow from the perspective of the North/South arrow.

Due to ___________

.

Trade winds or Easterlies: equator (0 °) to 30° N and S • Air returns across the surface of the earth__________ __________________________________ • It is deflected to the right in the Northern

hemisphere. • Moving N to S, right deflection= ________________. • NE trade winds between equator and 30° N (to SW)

• In Southern Hemisphere, the air is deflected to left. • Moving S to N, left deflection = towards the west • SE trade winds between equator and 30° S (to NW)

30° N

0°

Westerlies: 30°- 60° (both N & S), • Air moves from high pressure zone at 30° N

towards the poles. • Air moving from S to N in northern hemisphere

goes towards the _______________ Polar easterlies: poles(90 °) -60° from the east.

Microclimate- Local Climate Conditions A mountain range can affect the microclimate, because as air rises over the mountain range it ______ . _______ ____________________________________________.

The leeward side (downwind) of the mountain range is __________________________________________________________________________________________.

Discuss with your table partner:

Explain why the west coast of Peru is mostly a desert biome.

_____________________ _________________________________________________________________________________________________________________

__________________________________________ __________________________________________

Discuss with your table partner:

Explain the local wind patterns of land breezes and sea breezes. At what time of day do they occur?

__________________________________________________________________________________________________________________________________________________________________________________________________________________

Land breezes (from the land towards the sea) usually occur during the __________.

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Video: Mechanism of the Seasons http://www.youtube.com/watch?v=q4_-R1vnJyw Videos: Hadley Cell

http://www.youtube.com/watch?v=DHrapzHPCSA http://www.youtube.com/watch?v=T6Us1sPXBfA

Videos: Coriolis Effect

http://www.youtube.com/watch?v=_36MiCUS1ro (Watch to 2 minutes 45 seconds)

http://www.youtube.com/watch?v=aeY9tY9vKgs http://www.youtube.com/watch?v=i2mec3vgeaI

NASA Video: 10 Years of Weather in 3 Minutes. Observe general pattern of Easterlies and Westerlies.

•http://www.youtube.com/watch?v=ieILUnkdD90