Helping People Help the Land

Natural Resources 

Conservation Service

April 2015
Page 2

Let it Snowpack

rain

Snow falls

into warm air,

melts into rain.

Snow melts, refreezes 

into sleet as it travels

through cold air.

Snow falls into cold 

air, never melts on 

the way down.

Snow falls into warm

air, droplets of water

freeze on snowflakes.

sleet graupel snow

COLD AIR COLD AIR COLD AIR

hail

air flows upward

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What is Snow?

Snow is a form of precipitation. It falls to earth as a condensed form of 

water. The most common types of precipitation are: rain, snow, hail and 

sleet. 

Water turns into snow through a process called condensation. 

Condensation occurs when a vapor or gas converts to a liquid. When 

the temperature in the air is cool enough, the water vapor changes into 

tiny droplets of water. Once water vapor condenses into water, the 

droplets of water form clouds. When the temperature in the clouds is at or 

below 32 degrees Fahrenheit, the droplets of water freeze into tiny ice crystals 

that can fall as snow.

Graupel. Snowflakes that have become encrusted with ice. 

This happens when droplets of water freeze on snowflakes.

Hail. Forms when a frozen raindrop or graupel is kept 

from falling to the ground by air flowing upward in a 

thunderstorm. The more droplets that freeze onto the 

hailstone, the longer the hailstone spends in the sky. 

When it finally grows too heavy to be held up by the 

flowing air, hail falls to the ground.

Sleet. Drops of rain or drizzle that freeze 

into ice as they fall.

Snow is not the only type of ice that falls from the sky. Other forms of icy precipitation are:
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Let it Snowpack

The Shapes of Snow

Snow falls in many different crystal shapes. The global classification for snow crystals, ice crystals and 

solid precipitation is divided into several levels: general, intermediate and elementary. The general level 

has eight categories. Intermediate has 39 categories, and the elementary level has 121 categories!

Column crystal group (C)

Includes snow crystals that look similar to columns.

EXAMPLE: bullet-type crystal.

Next to each example picture, write in the letter for the category (group) to which it belongs.

Plane crystal group (P)

Snow crystals that are shaped similar to a 

hexagonal (six-sided) plate.

EXAMPLE: dendrite-type crystal. Dendrites, or 

branching extensions, make this type of plane 

crystal look like the typical snowflake.

Combination of column and plane crystals group (CP)

Snow crystals made of columns and planes.

EXAMPLE: six-pointed plane crystal with needle-type 

column crystals at the tip of each point.

Aggregation of snow crystals groups (A)

Snow crystals that come together to form a 

whole cluster of snow crystals.

EXAMPLE: aggregation of three different 

plane-type crystals.

Rimed snow crystal group (R) 

crystals that are coated with tiny ice crystals.

EXAMPLE: graupel. Looks like a circle of tiny ice crystals.

Germ of ice crystal group (G)

middle ice crystals that are less than 0.1 millimeters and 

often fall between the tropics and the Artic and Antarctic 

polar regions.

EXAMPLE: plane-type ice crystal is a simple hexagon.

Irregular snow particle group (I)

are raised from snow cover by strong winds. 

This type of ice crystal is very rare in nature.

EXAMPLE: broken snow particle.

Other solid precipitation group (H)

solid precipitation particles that are not snow crystals or 

ice. Three types from this group are shown on this page.

EXAMPLE 1: sleet particles (H2) have uneven shapes.

EXAMPLE 2: ice particles (H3) are round.

EXAMPLE 3: hailstones (H4) are round and bumpy. 

Eight General Lavel Categories
Page 4

Let it Snowpack

Layers of snowpack

the most recent snow

snow that has 

accumulated and 

compacted

snow that has 

melted and refrozen

hard layer contains 

more water than 

normal snow

Create your own avalanche

Phase 1

Phase 2

Phase 3

Put two books on the floor, one on top of the 

other, to represent the ground and a slab of 

snow. Slowly lift one end of the bottom book 

off the floor.

What does this experiment tell us about 

how some types of snowpacks are more 

likely to cause an avalanche than others?

How long did it take the slab of 

snow to start falling?

Sprinkle some salt 

between the two books to 

represent a layer of loose 

snow below the hard slab 

of snow on top. Slowly lift 

one end of the bottom 

book off 

the floor.

Add a third book above the top book to 

represent people hiking or skiing on top of the 

minutes seconds

How long did it take the slab of 

snow to start falling?

minutes seconds

How long did it take the slab of snow to start 

falling? minutes seconds snow. Sprinkle salt 

between the bottom 

book (ground) and middle 

book (snow) but not 

between the middle book 

and top book (people).

Snowpack and Its Layers

As snow and ice fall to the ground, they build layers of snow called snowpack. Snowpack is the total 

amount of snow and ice on the ground. In high mountain ranges, snowpack builds up in the winter and 

melts in the spring and summer. 

Layers within a snowpack vary and constantly change due to temperature changes in the air and within 

the snowpack. Some layers are weak, while other are strong. When the weak layers prevent the strong 

layers from sticking together, the strong layers slide over the weak layers. When snow begins to glide 

down a mountain, it is called an avalanche.
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Let it Snowpack

1. request

2.

respond

SNOTEL

Site

Master

Station

3. acknowledge

Measuring Snowpack

In 1935, the United States Department of Agriculture's (USDA) Natural Resources Conservation Service 

(NRCS) established a Snow Survey and Water Supply Forecasting Program. There are more than 1,200 

manually-measured snow courses and over 750 automated Snowpack Telemetry (SNOTEL) weather 

stations in 13 Western states, including Alaska. Since 50 to 80 percent of the water supply in the West 

arrives as snow, data on the snowpack provides information to decision makers and water managers 

throughout the West.

What’s at a SNOTEL site?

Use the alphabet key to fill in the boxes with the correct letters.

A = 1

C = 2

D = 3

E = 4

G = 5

H = 6

I = 7

K = 8

L = 9

M = 10

N = 11

O = 12

P = 13

R = 14

S = 15

T =16

U = 17

W = 18

Ice and Water

1. Gather snow (or ice from the freezer.)

2. Put it in a measuring cup.

3. Record the measurement of the ice.

4. Let it melt. Then record how much

water is in the measuring cup.

SNOTEL uses radio 

transmission by 

meteor burst. 

Radio signals 

are aimed skyward where 

the trails of meteorites 

reflect the signals 

back to earth.

ice:

water:

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Snow, Plants and Animals

In regions that receive a lot of snow, plants and animals have adapted to the 

snowy conditions. Plants, unlike animals, cannot escape harsh winter conditions. 

Plants have to stay put. Some plants are deciduous. They drop their leaves for 

part of the year and are able to save water since leaves tend to evaporate water 

into the air. Evergreen plants keep their leaves. Evergreen leaves and needles have 

thick, waxy coatings, helping reduce water loss. For places that receive more frequent snow, plants hold 

on to dead leaves for insulation or use deep snow like a blanket to protect against the cold. 

Adapt. Some animals have adapted to 

coexist with the cold. When it comes to 

adaptions, grazing animals use their 

hooves and muzzles to clear snow away 

from plants they need to survive. They 

also grow thicker hair or 

coats to keep them 

warm during the 

winter. They shed 

their coats when the 

weather is warm.

Migrate. Some animals 

leave the cold, snowy 

regions during the winter.

Across

1. Cold precipitation

4. Leave cold regions in the winter

6. Six-sided polygon

8. Snowpack Telemetry

10. Water falling to earth

11. Snow begins to glide down a mountain

13. Plants that drop their leaves for part of the year

14. Warm precipitation

16. Drops of rain that freeze into ice

as they fall

Down

2. Snowy season

3. Go into a deep, long winter sleep

5. A gas becomes a liquid

7. Change to survive

9. Total amount of snow and ice on

the ground

12. Snowflakes encrusted with ice

15. North polar region

Hibernate. Some animals, like bears and 

marmots, build a protective burrow and go 

into a deep, long sleep. The process is 

called hibernation. Hibernating animals 

build up fat reserves in the fall so they 

can survive during the winter months, 

usually not waking until spring.

However, animals’ survival is a bit different from 

plants. Since animals are not rooted to the ground, 

they have a few more options. Animals can:

Snow Crossword
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Let it Snowpack

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Make Your own Snowshoes

Before you begin to design and make your 

snowshoes, think about these two important factors:

1. The platform of the snowshoe must be 

much larger than your foot.

2. The platform must be firmly attached to your foot so 

it will not fall off. Choose the material for the platform. 

It could be any of the following recycled materials:

 Shoe boxes (the bigger, the better)

 Cardboard

 Gallon-sized plastic milk jugs

Choose the material for attaching 

the platform to your foot. Choose 

one of the following:

 Long shoelaces (or several 

 shoelaces tied together)

 Large, thick rubber bands

Strap the platform to your boot just before 

you are ready to go outside. Be careful 

when you walk. Lift your foot up high, just 

as if you were wearing flippers. You don’t 

want to trip over your big, snowshoed feet!

Snow and People

Snow is essential to humans. Many cities rely on melted snow to replenish their water supplies. By 

measuring the snowpack, NRCS is able to give water managers estimates of how much water will be 

available from the snowmelt. 

Agricultural producers also depend on snowmelt for their water needs. In Western states, many producers 

depend on diverted or stored water supply for irrigation. By using data from NRCS, landowners are able 

to make decisions about how much water will be available to water their crops. This helps them determine 

how much food they will be able to produce for the year. 

While snow is critical to our water and food supply, it is also a source of fun for those who like the 

outdoors. For more than 5,000 years, people have traveled long distances across snowy and icy 

landscapes. Ice skates, skis, sleds and snowshoes were invented to help travelers stay warm and travel 

quickly. In the Western states, many people use these tools for recreational activities.

You can make snowshoeing a fun activity wherever you 

live. Some kids like to snowshoe on soft surfaces, such 

as thick grass or pine needles. Kids at the beach enjoy 

snowshoeing through soft sand or over dunes. The 

main difference between these surfaces and the snow 

surface is their roughness. To protect the bottoms of 

their snowshoes from too much wear, these kids often 

put duct tape on the bottom of their snowshoes.

You Don’t Need Snow for Snowshoes
Page 8

Let it Snowpack

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S O L A R

P A N E L

A N T E N N

S E N S O R

S N O T E L

S H E L T E

P I L L O W

M A R K E R G R O U N D

S E N S O

D E P T H

G A U G E

P R E C I P I T A T I O N

S N O W

R

T R U T H

S N O W

R

T E M P E R A T U R E

A

S N O W

I M

H

N

T

ETO

N

D

C

L NS

R

H

I

B

E

C

X

R

A

A

G

T

O

E

N

R

N A

D

S

A

TIPICE

N

S

AVA L A N C H E

T

ICEDR

G

D U O U S

O

NIARU

R P

C E

T

I

C

L EES

A

A T RP

P

I O

W

P

A

C

K

N

N

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I N I M N P D E D U E B A E R

C T S E Q O L J I N J S N T S

E E E L T Y I A P S O D T A L

C E O T P O F T N L L O E R A

R L H I B E R N A T I O N G T

Y S S C M C L R K S S J N I S

S L W O N I P E H Z N O A M Y

T N O I T A T I P I C E R P R

A R N M N T L A K U H U D I C

L V S E H U M A N S A A W N W

S K L W A T E R V I T R I O O

C S N O W P A C K A M P G L N

S S U O U D I C E D G A A D S

O G N I H S I F S C R N L D N

D G N I I K S K V V P V J S A

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ANSWER KEY

C

CP

A

H2

G I

H4

H3

R

P

ADAPT

ANIMALS

ANTENNA

AVALANCHE

CONDENSATION

DECIDUOUS

FISHING

GRAUPEL

HAIL

HIBERNATION

HUMANS

ICE

ICECRYSTALS

MELT

MIGRATE

PLANTS

PRECIPITATION

SKIING

SLEET

SNOW

SNOWCRYSTALS

SNOWPACK

SNOWSHOES

SOLARPANEL

WATER

N I M N P D E D U E B A E R I

T S E Q O L J I N J S N T S C

E E L T Y I A P S O D T A L E

E O T P O F T N L L O E R A C

L H I B E R N A T I O N G T R

S S C M C L R K S S J N I S Y

L W O N I P E H Z N O A M Y S

N O I T A T I P I C E R P R T

R N M N T L A K U H U D I C A

V S E H U M A N S A A W N W L

K L W A T E R V I T R I O O S

S N O W P A C K A M P G L N C

S U O U D I C E D G A A D S S

G N I H S I F S C R N L D N O

G N I I K S K V V P V J S A D

Snow Word Search

Circle all the words from this list 

that you can find. Hint: some are 

spelled backwards.

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