Digging Deeper
Weather and Climate Pages E91 – E94
What is “Weather”?
• The term “weather” refers to the state of the atmosphere at a specific time and
place.
• Weather can change from day to day and week to week.
Example of a U.S. Weather Map
What is “Climate”?
• The term “climate” refers to the general pattern of weather conditions for a region over a long period of time (at least 30
years).
• Climate is influence by:
– Latitude – Elevation
– Nearby geologic features
How Does Latitude Influence Climate?
• Latitude is a measure of how far north or
south a location is from the equator.
The amount of solar energy a location receives depends on its latitude
• The sun strikes the Earth more directly at the equator and is
more “spread out” at the poles.
As a result…
• Temperatures go down a degree
Fahrenheit for every three degrees latitude away from the equator.
Elevation
As you go up a mountain, the temperature drops. This is why you see glaciers on the tops of mountains. Temp. drops about 3-4 degrees for every 1000 feet up.
There will also be different living
things at different elevations because of the change in temperature.
Look for the change in plants as you go up the mountain in these next
pictures.
Geographic Features
• Geographic features, like mountain
ranges, lakes, and oceans, affect climate.
Windward vs. Leeward Side
Mountains affect climate.
Windward side of mountain receives more rain.
Why?
Wind approaches the windward side of mountain, air is forced up and cooled.
The cooling air can’t hold as much water and the water condenses into clouds and which produce rain.
Seattle vs. Spokane
Large Bodies of Water Affect Climate
• When it’s really cold outside (5o F) what is the water temp.?
• When it’s really hot (95o F) what is the temp. of the water?
• So…the land near water is moderated (evened out) by this.
Seattle vs. Minneapolis-St. Paul
Lake-Effect Snow
• Common in areas east of the Great Lakes (Buffalo, NY) In autumn and early winter.
• Cold winds blow across the still-warm water, accumulating moisture from the lake.
• When the winds reach the cold land, the air is cooled, and the water precipitates out of the clouds as snow.
This can result in very high
amounts of snowfall
Regional vs. Global Climate
• The term “Regional Climate” refers to the climate (average temperature,
precipitation, etc…) of a region.
• Climates differ from one region to another, depending on latitude, elevation, and
geologic features.
• The term “global climate” refers to the year-round average temperatures of the entire surface of the Earth.
Global Climate
• Today, the average temperature of the surface of the Earth is about 60oF.
• The Earth’s climate has changed continually over geologic time:
During the Age of Dinosaurs, the
Earth was warmer than today.
From 1.6 million to 10,000 years ago,
the Earth was cooler than today.
The “Little Ice-Age”
• Term to describe a time during which significant glacial advances were
observed.
• It has come to be used to characterize a time from around A.D. 1300 to 1450 until A.D. 1850 to 1900 during which regional evidence in Europe and elsewhere
suggest generally cold conditions.
Natural Temperature Changes
• Discussions of global warming bring often argument that the world experienced
significant temperature changes in the past.
• It is claimed that we had the so-called
Medieval Warm Period (1000-1300 AD), with temperatures allegedly comparable
with the present temperatures, followed by the Little Ice Age (1400-1900) with
excessively low temperatures.
A look at the data…
• There is no sign of any distinct periodic behavior that we could identify as the so- called Medieval Warm Period and the
Little Ice Age.
• The data show a steadily decreasing trend in the first 900 years.
Was it Global??
• Even though your text indicates that the Little Ice-Age (LIA) was a time of global cooling, there is evidence that it was
something that occurred mainly in Europe, not worldwide.
• It may have been caused by local climate factors including changes in wind and
ocean current patterns.
• We have no problem to see a clear and undeniably rapid increase in the mean temperature after 1900.
• The Northern Hemisphere data for the last millennium show a clear net drop of 0.2°C in the mean surface temperature in the
first 900 years, followed by an increase of 0.8°C in the last 100 years.
Test Questions!
• The following slides have questions that will be on your chapter test.
• It is encouraged that you copy them down or take notes about them!
• This will enable you to more easily prepare for the chapter test!
Test Questions
1. What is the elevation of point A on the map?
a) 1200 meters b) 1200 feet c) 1300 meters d) 1300 feet 2. What physiographic feature
(landform) is found at location B?
a) a cliff b) a valley c) a hill d) a plain
3. On this map, in which direction is north?
a) towards the top of the page b) to the right
c) towards the bottom of the page d) to the left
4. A high coastal mountain range is on the western coast of a continent. Warm moist air blows from west to east over the mountains. From this information you would expect the western side of the mountain range to have __________________ compared to the eastern side of the mountain range.
a) more annual precipitation b) less annual precipitation c) hotter summers
d) cooler winters
e) the same climate
5. Two cities are located at approximately the same
latitude. City A is located on an island in the ocean, and city B is located in the middle of a continent. Both cities are at the same elevation. All other aspects about their physical environments are identical. On the basis of these observations, which of the following is a valid conclusion?
a) City A would tend to have warmer summers and cooler winters than city B.
b) City A would tend to have cooler summers and warmer winters than city B.
c) The two climates would be the same because the cities are at the same latitude.
d) City A would have a shorter winter and longer summer compared to city B.
Last one for today
6. Which of the following factors or concepts distinguishes climate from weather?
a) Accuracy of prediction.
b) Kinds of measurements.
c) Time scale of observations.
d) Size of an area.
Assignment
• In your notebook:
– Open your book to P. E94
– Answer “Check Your Understanding”, questions 1-5
– Period 2: Add “Preparing for the Chapter Challenge,
