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Why Desert Nights Turn Cold

5th grade nonfiction passage about desert temperature swings: 231 words, six questions, an answer key and vocabulary.

5th grade nonfiction desert temperature swings 231 words

Why Desert Nights Turn Cold

Imagine a hiker in a desert. At noon the sun is fierce, and the hiker wears a hat and drinks lots of water. After dark, the same hiker pulls on a jacket and shivers. In many deserts, the air can feel more than twenty degrees cooler at night than it did during the long, bright afternoon, and that change surprises most visitors. Why does such a hot place get so chilly after the sun goes down?

The answer has to do with water in the air. Humid places hold a lot of water vapor, and vapor acts a bit like a blanket. It helps trap heat near the ground. Deserts are dry, so the air holds little vapor. The sky is often clear, too, with few clouds. Clouds also slow the loss of heat.

During the day the sun heats the sand and rock. Plants are few, so there is little shade to block the light. Once the sun sets, the ground sends its warmth back up into the sky. With no blanket of vapor or cloud, the heat escapes quickly, and the air cools off fast.

Desert animals have found ways to live with these swings. Many rest in burrows or in the shade during the heat of the day. Then they come out to hunt and look for food after the sun goes down, when the air is gentler.

Questions

  1. How much cooler can desert air feel at night than in the afternoon? in the text

  2. What does water vapor do in humid air? in the text

  3. Why do clear skies make nights colder? think about it

  4. What happens to the ground's heat after the sun sets? in the text

  5. Why do many desert animals come out after dark? think about it

  6. Why does a desert have little shade? in the text

Words to know

fierce
very strong and intense
humid
full of moisture, or damp
trap
to hold something so it cannot get away
burrows
holes or tunnels dug in the ground by animals
shade
a cool, darker spot out of the sunlight
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One passage, three levels

The same topic and facts written three ways, so a mixed class can read and talk about one text. Each group’s sheet shows only a shape; the key says which is which.

● Easier · 183 words · Flesch-Kincaid grade 2.2

Picture a hiker in a desert. At noon, the sun is strong. The hiker wears a hat and drinks lots of water. After dark, the hiker puts on a jacket and shivers. In many deserts, the air can be more than twenty degrees cooler at night. Why does a hot place get so cold?

The answer is water in the air. Humid places have a lot of water vapor. Vapor works like a blanket. It helps keep heat near the ground. Deserts are dry, so the air has little vapor. The sky is often clear, too, with few clouds. Clouds also keep heat in.

In the day, the sun heats the sand and rock. Plants are few, so there is little shade. When the sun sets, the ground sends its warmth back up into the sky. There is no blanket of vapor or cloud. The heat escapes fast, and the air cools quickly.

Desert animals live with these swings. Many rest in burrows or in the shade in the day. They come out to find food after dark, when the air is cooler.

▲ This passage · 231 words · Flesch-Kincaid grade 3.9

Imagine a hiker in a desert. At noon the sun is fierce, and the hiker wears a hat and drinks lots of water. After dark, the same hiker pulls on a jacket and shivers. In many deserts, the air can feel more than twenty degrees cooler at night than it did during the long, bright afternoon, and that change surprises most visitors. Why does such a hot place get so chilly after the sun goes down?

The answer has to do with water in the air. Humid places hold a lot of water vapor, and vapor acts a bit like a blanket. It helps trap heat near the ground. Deserts are dry, so the air holds little vapor. The sky is often clear, too, with few clouds. Clouds also slow the loss of heat.

During the day the sun heats the sand and rock. Plants are few, so there is little shade to block the light. Once the sun sets, the ground sends its warmth back up into the sky. With no blanket of vapor or cloud, the heat escapes quickly, and the air cools off fast.

Desert animals have found ways to live with these swings. Many rest in burrows or in the shade during the heat of the day. Then they come out to hunt and look for food after the sun goes down, when the air is gentler.

■ Harder · 218 words · Flesch-Kincaid grade 6.1

Imagine a hiker crossing a desert. At midday the sun is merciless, and the hiker wears a wide hat and drinks plenty of water. After dark, the same hiker pulls on a heavy jacket and shivers. In many deserts, the air can feel more than twenty degrees cooler at night than it did in the afternoon. How can such a scorching place become so chilly?

The explanation involves the moisture in the air. Humid regions hold a great deal of water vapor, and vapor behaves somewhat like a blanket, helping to trap heat close to the ground. Deserts are dry, so their air contains very little vapor. The sky is frequently cloudless as well, and clouds also slow the escape of heat.

During the day, the sun bakes the sand and rock. Plants are scarce, so there is hardly any shade to block the light. Once the sun sets, the ground radiates its warmth back into the sky. With no blanket of vapor or cloud to hold it in, the heat escapes rapidly, and the air cools off quickly.

Desert animals have adapted to these dramatic swings. Many shelter in burrows or in the shade during the heat of the day, and then emerge to hunt and forage after the sun goes down, when the air is gentler.

Download as one PDF

How to use it

  1. Press Read it big (or B) to put the text on the projector, or Full screen (F) to fill the whole screen.
  2. Ask the questions one at a time and use Show answer when the class has decided. A shows or hides every answer.
  3. Print student copy for the class, or Print with answers for yourself.

Ideas for class

  • Before reading, put fierce, humid, trap, burrows and shade on the board with their meanings from the Words to know section and have students predict what the text will be about.
  • Read it aloud once while students follow along, then have them reread it alone or with a partner. At a calm 100 words a minute it takes about 2 minutes to read aloud.
  • Use the Read it big button (or B) to put the text on the projector, and Show answer on one question at a time so the class commits to an answer first.
  • Question 3 asks the reader to infer. Ask students to point to the words in the passage that led them to their answer.
  • Ask students to write one question the passage did not answer, then look for the answer in a book or on a classroom screen.
  • Print the student copy for independent work and keep the answer-key copy for yourself.

Related

Questions

What reading level is "Why Desert Nights Turn Cold"?

It was written for 5th grade. It has 231 words and works out to a Flesch-Kincaid grade level of about 3.9. That is a formula's estimate from sentence length and syllables, and it is not a Lexile or a guided reading level, so check it against your students.

What do the questions ask?

There are six. 4 ask for something the text says directly and 2 ask the reader to work something out from clues. Each has an answer in the key, and the answers are written as a teacher would accept them, not as the only possible wording.

How long does it take to read?

About 2 minutes read aloud at 100 words a minute. For a one-minute fluency check, paste it into the fluency timer and use the word count.

Can I print it?

Yes. Print student copy gives the passage, the questions with lines to write on, and the word meanings. Print with answers gives the same page with the answers filled in. Both are made in your browser.

Is this passage from a published book?

No. It was written for Peabody Teach, so there is no book to buy and no login to read it.

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