Chapter 3 Seasonal and Daily Temperatures

Question 1

When is the earth closest to the Sun?

Answer 1

in January (147 million km)
farthest in July (152 million km)

Question 2

Why do we have seasons?

Answer 2

the earth is tilted on an angle meaning certain areas of the world get more sunlight during specific months than others

Question 3

how much is the earth tilted by?

Answer 3

23.5 degrees

Question 4

What happens during March 21st?

Answer 4

Spring Equinox
direct light: @ Equator (0 deg. N)
areas w/ 24 hours of light: N/A, all get 12
areas w/ 0 hours of light: N/A, all get 12
season that starts in NH: Spring
season that starts in SH: Fall

Question 5

What happens on June 21st?

Answer 5

Summer Solstice
direct light: @ Tropic of Cancer (23.5 deg. N)
areas w/ 24 hours of light: Arctic Circle (66.5 deg. N - 90 deg. N)
areas w/ 0 hours of light: Antarctic Circle (66.5 deg. S - 90 deg. S)
season that starts in NH: Summer
season that starts in SH: Winter

Question 6

what happens on September 21st?

Answer 6

Fall Equinox
direct light: @ Equator (0 deg. N)
areas w/ 24 hours of light: N/A, all get 12
areas w/ 0 hours of light: N/A, all get 12
season that starts in NH: Fall
season that starts in SH: Spring

Question 7

what happens on December 21st?

Answer 7

direct light: @ Tropic of Capricorn (23.5 deg. S)
areas w/ 24 hours of light: Antarctic Circle (66.5 deg. S - 90 deg. S)
areas w/ 0 hours of light: Arctic Circle (66.5 deg. N - 90 deg. N)
season that starts in NH: Winter
season that starts in SH: Summer

Question 8

how many times do the tropics get direct sunlight?

Answer 8

the tropics get it once a year, everything in between gets it twice a year

Question 9

what happens when you get closer to the poles?

Answer 9

there is a greater variation in hours of daylight

Question 10

if the North Pole gets 24 hours of sunlight for several months, why does it not get hotter than everywhere else?

Answer 10

even though it gets 24 hours of daylight, it’s at a low angle and not direct sunlight. The poles also have lots of snow increasing the areas albedo

Question 11

Even though the earth is the closest to the sun during SH’s summer, why is its weather similar to NH’s in the summer?

Answer 11

there is a greater amount of water absorbing heat and the SH summer is shorter than NH’s summer

Question 12

Why is December 21st technically the “first day of winter?”

Answer 12

it is the astronomical first day of winter because the sun passes over the Tropic of Capricorn, not related to temperature

Question 13

What is daytime heating?

Answer 13

1) ground heats up from sun radiation
2) initial heating only affects air near ground (air is poor conductor)
3) convection begins as energy builds and heat moves higher up
4) atmosphere gets most temperature 2-5 hours after area received most solar radiation (around noon)

Question 14

what is Night Time Cooling?

Answer 14

lower solar angle causes insolation to be spread across a larger area

Radiational cooling: ground continues to emit IR radiation so it cools

Radiation inversion: air near ground is cooler than air above

Question 15

When are inversions strongest?

Answer 15

long nights (winter)
clear nights (no clouds)
dry nights (not humid)
calm nights (no wind)

Question 16

What is a thermal belt?

Answer 16

when cold air sinks and settles in valleys so there is a layer of warm air trapped between two layers of cold air

Question 17

what are the five types of air temperature data?

Answer 17

Range: max minus min
Mean: average of temp. observations
Maximum: highest temp. of time period
Minimum: lowest temp. of time period
Anomaly: departure from mean

Question 18

For altitude data, what occurs at a higher elevation?

Answer 18

higher elevation means smaller range between daily max and daily min. Less day/night variation farther from the surface

Question 19

what does temperature data look like with clouds?

Answer 19

clouds keep daytime temp lower by bouncing the suns rays off of them

clouds keep night time temp high by trapping in IR radiation from the earth

smaller daily range

Question 20

what does temperature data look like in the absence of clouds?

Answer 20

days are warmer since the surface has direct access to the suns rays

nights are color since the IR radiation is free to escape

large range in temperature

Question 21

how does water affect temperature data?

Answer 21

it reduces range, I don’t know why

Question 22

what information do degree-days/points give us?

Answer 22

65 deg. F is the average comfortable temperature. If we want to heat our house we must subtract the daily mean temp by 65 to find out by how much. If we want to cool our house we must subtract 65 by the daily mean temp to find out how much. Let’s us know how much energy we need.

(need heat) heating degree=65-T
(need A/C) cooling degree=T-65

Question 23

what is the wind-chill index?

Answer 23

warm air molecules form close to skin on a cold day. once the wind blows, the layer is swept off making us colder.

Wind chill combines temp with wind speed to tell us how cold it feels with given conditions

Question 24

what is the heat index?

Answer 24

the body cools itself by sweating and waiting for that sweat to evaporate. When relative humidity is high, evaporation rates are low. Heat is removed from body at a lower rate.

Heat index compares temp. with relative humidity to tell how it feels under certain conditions

Question 25

what are three ways to measure air temp?

Answer 25

bulb thermometers: liquid expands as air temp increases
spring thermometers: uses strips of metal that expand at different rates to sense temperature
thermoelectric thermometers: uses an electronic sensor to generate electric voltage **Digital

method matters

Question 26

what are the four main controls of temperature?

Answer 26

1) Latitude: solar angle and day length
2) Land & Water: specific heat higher for water
3) Ocean Currents: warm and cold currents cause bend in isotherms
4) Elevation: cooling and decreased range with height

Question 27

What four factors affect interannual temperature variations?

Answer 27

1) el niño (+), el niña (-)
2) volcanoes (-)
3) solar output (?)
4) greenhouse gases (+)