Chapter 3 Seasonal and Daily Temperatures Flashcards
When is the earth closest to the Sun?
in January (147 million km)
farthest in July (152 million km)
Why do we have seasons?
the earth is tilted on an angle meaning certain areas of the world get more sunlight during specific months than others
how much is the earth tilted by?
23.5 degrees
What happens during March 21st?
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
What happens on June 21st?
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
what happens on September 21st?
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
what happens on December 21st?
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
how many times do the tropics get direct sunlight?
the tropics get it once a year, everything in between gets it twice a year
what happens when you get closer to the poles?
there is a greater variation in hours of daylight
if the North Pole gets 24 hours of sunlight for several months, why does it not get hotter than everywhere else?
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
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?
there is a greater amount of water absorbing heat and the SH summer is shorter than NH’s summer
Why is December 21st technically the “first day of winter?”
it is the astronomical first day of winter because the sun passes over the Tropic of Capricorn, not related to temperature
What is daytime heating?
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)
what is Night Time Cooling?
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
When are inversions strongest?
long nights (winter)
clear nights (no clouds)
dry nights (not humid)
calm nights (no wind)
What is a thermal belt?
when cold air sinks and settles in valleys so there is a layer of warm air trapped between two layers of cold air
what are the five types of air temperature data?
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
For altitude data, what occurs at a higher elevation?
higher elevation means smaller range between daily max and daily min. Less day/night variation farther from the surface
what does temperature data look like with clouds?
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
what does temperature data look like in the absence of clouds?
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
how does water affect temperature data?
it reduces range, I don’t know why
what information do degree-days/points give us?
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
what is the wind-chill index?
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
what is the heat index?
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
what are three ways to measure air temp?
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
what are the four main controls of temperature?
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
What four factors affect interannual temperature variations?
1) el niño (+), el niña (-)
2) volcanoes (-)
3) solar output (?)
4) greenhouse gases (+)
