0 comments on “The Energy of a Hurricane: crackpot attempts to mitigate hurricane damage”

The Energy of a Hurricane: crackpot attempts to mitigate hurricane damage

Here’s a beautiful photo of Hurricane Irene as it makes its way up the East Cost this weekend (tomorrow is Saturday, Sunday comes afterwards).

There have been a few hair-brained schemes to mitigate the intensity of a hurricane throughout the years. I say “hair-brained” because it seems highly unlikely that either of these could potentially affect the path or strength of a hurricane. It’s simply a question of the amount of energy produced by a hurricane (which is a lot) compared with the energy released by giant blocks of ice and nuclear warheads (which are comparatively small). Those are the hurricane mitigation attempts that I’d like to focus on. Because while they may be “hair-brained” they can prove to be instructive about environmental science, geometry, and calculus.


  • Mitigating hurricane damage by
    • Using giant blocks of ice to cool the sea surface temperature (SST).
    • Detonating a nuclear bomb inside a hurricane.

Guiding questions

  • How big would a block of ice have to be to cool the SST in front of a hurricane by, let’s say, one degree Celsius?
  • Wouldn’t a lot of that ice melt on its way down from the arctic?
  • How much energy does an atomic bomb have compared to a hurricane?

Suggested activities

  • Research the amount of energy in a hurricane.
  • Calculate the distance from the arctic to the Atlantic hurricane basin, and speed at which a naval vessel could transport the gigantic block of ice.
  • Research the amount of energy released by a nuclear bomb.
  • Have groups decide which method is a more feasible achievement.

Potential solutions

Well, let’s look at the energy of a hurricane. Take it away, NOAA.

One can look at the energetics of a hurricane in two ways:

  1. the total amount of energy released by the condensation of water droplets or …
  2. the amount of kinetic energy generated to maintain the strong swirling winds of the hurricane (Emanuel 1999).

It turns out that the vast majority of the heat released in the condensation process is used to cause rising motions in the thunderstorms and only a small portion drives the storm’s horizontal winds.

  • Method 1) – Total energy released through cloud/rain formation:An average hurricane produces 1.5 cm/day (0.6 inches/day) of rain inside a circle of radius 665 km (360 n.mi) (Gray 1981). (More rain falls in the inner portion of hurricane around the eyewall, less in the outer rainbands.) Converting this to a volume of rain gives 2.1 x 1016 cm3/day. A cubic cm of rain weighs 1 gm. Using the latent heat of condensation, this amount of rain produced gives5.2 x 1019 Joules/day or
    6.0 x 1014 Watts.
    This is equivalent to 200 times the world-wide electrical generating capacity – an incredible amount of energy produced!
  • Method 2) – Total kinetic energy (wind energy) generated:For a mature hurricane, the amount of kinetic energy generated is equal to that being dissipated due to friction. The dissipation rate per unit area is air density times the drag coefficient times the windspeed cubed (See Emanuel 1999 for details). One could either integrate a typical wind profile over a range of radii from the hurricane’s center to the outer radius encompassing the storm, or assume an average windspeed for the inner core of the hurricane. Doing the latter and using 40 m/s (90 mph) winds on a scale of radius 60 km (40 n.mi.), one gets a wind dissipation rate (wind generation rate) of1.3 x 1017 Joules/day or
    1.5 x 1012Watts.
    This is equivalent to about half the world-wide electrical generating capacity – also an amazing amount of energy being produced!

That’s a lot of joules/day, easily dwarfing the release of a (and several!) nuclear warheads. As for the giant block of ice…

Well, the specific heat of water is about 4 joules/gram, which means that it would take 4 joules of energy to raise or lower one gram of water by one degree Celsius. Water weighs about 1000 kg per cubic meter. If you want to cool a swath of ocean, say, 3000 sq km to a depth of two meters, then that’s,

3000 x 2 x 1000 = 6 million kg of water

It would take a lot of ice to cool that much water by a single degree. And hurricanes span a lot more than 3000 sq. km.

But for this instance, you would need 24,000,000,000 joules of energy from the ice.

The latent heat of ice is 334 kJ/kg. So my back-of-the-envelope calculation (this is all very scientific) tells me that we need

24,000,000,000 J x 1 kJ/1000 kJ x 1 kg/334 kJ = 12,000,000 kg of ice

And that’s at the point of the hurricane. And that’s one degree. How big is 12,000,000 kg of ice, anyway? Another, possibly more interesting more interesting question is a calculus problem: how much ice would melt before we got it to the hurricane. Better yet: how much ice would we have to start with in order to have 12,000,000 kg of ice by the time we get to the Atlantic?

Oh my ice-melting/calculus sense is tingling!

10 comments on “The “Don’t Teach Them Content on Day 1” Myth”

The “Don’t Teach Them Content on Day 1” Myth

I’ve often been told by teachers and administrators to neglect teaching Math to students on Day 1 of the school year. In some cases, teachers and administrators prefer to spend a full week on culture building activities. Another typical model of year-starting schedules might have, say, the Math Teacher facilitate culture building activities, the Social Studies Teacher develop classroom rules and norms, the Science Teacher curate school pride, etc.

The thinking (which I think is basically correct) is that “sure, you lose a bit of time on these activities, but then the students will soar once these activities are completed.” I totally understand that. All these are wonderful and essential things to address those first few weeks of school, particularly if yours is a new school startup. The idea is if you have a good class culture, the teaching of content will fall into place.

However, there’s a implication buried deep within this line of thinking:

My content isn’t able to build culture.

My content isn’t able to promote and develop classroom norms.

My content isn’t able to curate school and class pride.

So it has to be taught separately from these other positive things.

That’s probably not the intended message by “not teaching content” at the beginning of school, but that’s the message I hear. And I wonder if it’s the message your students hear: “Math is so boring that we’re better off building culture before we get to the boring stuff.”

Perhaps this is a benign messaging problem, but I fear it’s symptomatic of a much more ingrained structural problem: a problem with way we sometimes teach content. Because content is so often separated from school culture, they are seen as separate entities. It’s not hard to see why when you spend a week building your classroom culture with group activities and Socratic dialogue, followed by lecture,practice,lecture,practice,lecture,practice… When teaching is unengaging, you certainly need to butress it with culture and class rules and norms. But that’s probably a post for another day.

Flipping the statement from above, I can’t tell if this is an obvious statement or a challenging one: if you’re teaching content well, the class culture stuff will fall into place.

Imagine if you were able to both engage students in your content area while at the same time developing a positive classroom culture, establishing norms, fostering school pride, etc. Why not use your content area as the tool of culture-building, rather than a follow-up to culture-building? That has the potential to change students’ minds about your content area. If students see your content area as a place where you can develop these positive norms, that can have lasting repercussions for your students even beyond your classroom.

That requires getting students engaged in math (or whatever) on Day 1, not Week 2, on a level that gets them working together.

Clearly I’m not expecting an intensive investigation on vector calculus on Day 1 when your kids don’t even know where to sit yet. But if this is your first day with your students, and you want to set them up for a year-long investigation in mathematics at a deep level, then shouldn’t math be the first thing they encounter?

I’m also not suggesting that you eschew culture-building or norm-establishing entirely, but rather that it be an organic outcome of the student-centered instruction that begins from the first minute of class. Maybe at the end of the week, debrief with students, asking them what they liked and disliked about the weeks’ math activities – there are your classroom norms and expectations.

You know that famous fox-chicken-lettuce-boat (or other variation) problem? The purpose of that problem is to get students to talk and discuss a way through the problem in a collaborative manner. Ideally, once the students have completed the problem, then (and only then?) will you have the foundation to teach mathematics. But what if that were a math problem instead? What if students were just as engaged and conversational in a math problem as they are the river-crossing problem?

So this year, consider: rather than conducting culture building activities on Day 1, followed by the rushing in of non-culture-building content, think about your content as the culture-building activity.

I would consider a successful first-day/week activity something that achieves the following:

  • Gets students working collaboratively .
  • Gets student thinking about your content.
  • Allows for all students to be successful initially.

(Note: that these are also attributes of a successful 74th day activity.)

Here are some things I have done in the past and/or have discovered online that might be a nice Day 1 math activity. But keep in mind, the activity may not need be anything other than an engaging, interesting problem. Feel free to post any additional ideas for math or for other content areas in the comments below!

  • An #anyqs activity. This would be a great way of establishing the norm that you want students to be the question-askers, rather than the teachers.
  • Geometry puzzles sort of like these.
  • Something akin to The Tower. (from Action-Reaction)
  • Groups organize themselves into Venn diagrams by interests, schedules, personality traits, etc.
  • Something with Gapminder. What exactly, I’m not quite sure….. I’m thinking of having the groups research two sets of data (their choice, of course!) and present their findings about the correlation throughout the years.
  • Students research and describe themselves as kinds of numbers: rational, irrational, imaginary, improper fractions, integers, etc.
  • This, or a similar, interesting, conversation-producing activity on “squareness” from Always Formative.
  • Lots more great first day activities that will get students engaged in math here.