Seasonal Changes in Seasonal Changes in Sea Ice AreaSea Ice Area

Presented by Rob SnyderPresented by Rob Snyder

Earth’s Cryosphere consists of all forms Earth’s Cryosphere consists of all forms of water in the solid state and includes:of water in the solid state and includes:

Sea IceSea Ice

Lake IceLake Ice

SnowSnow

GlaciersGlaciers

Ice CapIce Cap

Sheet IceSheet Ice

PermafrostPermafrost

Ice in CloudsIce in Clouds

Sea Ice FormationSea Ice Formation

Ways to explore the seasonal Ways to explore the seasonal changes in the extent of sea ice area changes in the extent of sea ice area include:include:

• Interpreting graphsInterpreting graphs

• Working with modelsWorking with models

• Viewing images and animationsViewing images and animations

• Hands-on activitiesHands-on activities

• Research activitiesResearch activities

Interpreting Sea Ice Area GraphsInterpreting Sea Ice Area Graphs

Half of you will interpret a graph for the Half of you will interpret a graph for the Southern Hemisphere.Southern Hemisphere.

Half of you will interpret a graph for the Half of you will interpret a graph for the Northern Hemisphere.Northern Hemisphere.

Note: Later this week, you will actually make sea ice.Note: Later this week, you will actually make sea ice.

The Northern Hemisphere group The Northern Hemisphere group will interpret this graph.will interpret this graph.

http://arctic.atmos.uiuc.edu/cryosphere/

The Southern Hemisphere group The Southern Hemisphere group will interpret this graphwill interpret this graph..

When was the maximum of When was the maximum of sea ice area for the sea ice area for the entire entire Earth during the last 365 Earth during the last 365

days?days?

Maximums and minimums of the sea ice area Maximums and minimums of the sea ice area graphs correspond closely with the changes in graphs correspond closely with the changes in “Astronomical“ seasons in both Hemispheres.“Astronomical“ seasons in both Hemispheres.

http://okfirst.mesonet.org/train/meteorology/Seasons.html

Why would the sea ice minimum Why would the sea ice minimum in the Northern Hemisphere occur in the Northern Hemisphere occur around the time of a Fall Equinox around the time of a Fall Equinox rather than around the time of a rather than around the time of a Summer Solstice?Summer Solstice?

This graph reveals the pattern of change This graph reveals the pattern of change in the length of daytime. in the length of daytime.

Is this a graph for the Northern or Southern Hemisphere?Is this a graph for the Northern or Southern Hemisphere?

http://www.eoearth.org/article/Earth-Sun_relationships_and_insolation

During the entire summer, the lengths of daytimes During the entire summer, the lengths of daytimes are greater than the lengths of nighttimes. The altitude are greater than the lengths of nighttimes. The altitude of the sun is also higher during summer monthsof the sun is also higher during summer months

http://www.azsolarcenter.com/design/pas-2.html

This year’s Northern Hemisphere’s This year’s Northern Hemisphere’s Autumnal Equinox and the Autumnal Equinox and the Southern Southern

Hemisphere’s Vernal EquinoxHemisphere’s Vernal Equinox will begin at 20:18 UT (16:18 EDT) will begin at 20:18 UT (16:18 EDT)

on September 22nd.on September 22nd.

Why does that happen at one specific Why does that happen at one specific moment in time?moment in time?

A “Globe Walk” activity/demonstration A “Globe Walk” activity/demonstration provides an opportunity for students to use provides an opportunity for students to use models to:models to:

Develop an understanding of the Develop an understanding of the seasonal changes in the “altitude” of the seasonal changes in the “altitude” of the sun and the lengths of daytimes in the sun and the lengths of daytimes in the Polar Regions.Polar Regions.

Develop an understanding of how the Develop an understanding of how the time and dates are determined for the time and dates are determined for the changes of the astronomical seasonschanges of the astronomical seasons..

• Views of the extent of sunlight in Views of the extent of sunlight in the Polar Regions as the seasons the Polar Regions as the seasons change.change.

• The location on Earth where the The location on Earth where the midday sun is directly overhead as midday sun is directly overhead as the seasons change. the seasons change.

http://aa.usno.navy.mil/data/docs/earthview.php

A United States Naval Observatory A United States Naval Observatory web site can be used to provide:web site can be used to provide:

What are some additional questions What are some additional questions that could be posed that relate to that could be posed that relate to

the sea ice area graphs?the sea ice area graphs?

Research ActivitiesResearch Activities

• Use images from web sites to Use images from web sites to monitor snow cover and sea ice in monitor snow cover and sea ice in the Polar Regions and at lower the Polar Regions and at lower latitudes during the school year.latitudes during the school year.

• Use archives on web sites to Use archives on web sites to compare the present accumulation of compare the present accumulation of sea ice and snow with past years and sea ice and snow with past years and with “normal” years.with “normal” years.

The Cryosphere Today’s web site can be used to The Cryosphere Today’s web site can be used to compare the extent of sea ice and snow cover compare the extent of sea ice and snow cover

in both hemispheres.in both hemispheres.(The color scale applies only to the extent of sea ice.)(The color scale applies only to the extent of sea ice.)

http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=11&fd=15&fy=2008&sm=02&sd=15&sy=2009

Building an Understanding of the Seasonal Changes in Sea Ice Area

• Investigate a wide range of implications of changes in the climate of the Polar Regions.

• Conduct both short term and long term investigations.

• Utilize a wide range of resources. • Continue the development of essential

investigative skills and scientific knowledge.