Two things about Almanzo Wilder’s story, in particular, that confuse me:
One night, the corn froze, and everyone had to pour water over the corn plants in the field, before the Sun’s light touched it. Why would Sun kill frozen corn plants and how would pouring water over the plants help?
After a long trek in the winter, Almanzo’s brother rubbed snow over his numbed feet to save them from frostbite. How does that do any good?
This website suggests the water would have seemingly paradoxically warmed the plant when the water froze. The danger from the sun seems like it would be that evaporative cooling as the ice melted and the water evaporated would be as, if not more, dangerous to the plant than the frost.
And old SDMB thread has some ideas about the snow to prevent frostbite but note, it is not recommended frostbite treatment!
Not a biologist, but it seems to me pouring water over the corn would defrost the entire plant at once, rather than having some part defrost sooner than others. (Liquid water is warmer that freezing) if you recall news reports, Florida orange growers do something similar, they spray oranges during a sudden cold snap. The water coats the trees and oranges, and the outer layer of water freezes during the night instead of the oranges or tree branches. The ice provides a somewhat insulating layer.
I don’t know how accurate the science is about rubbing snow on, but for warm-blooded animals whose cells use energy, you want to defrost from the inside out, so outer cells (skin, toes) do not defrost in the warm cabin before the blood from inside reaches it to help feed it. Of course, if it freezes too solid, the ice crystals wreck the cells and defrost order doesn’t matter. But in the cold, the outer blood vessels shrink closed first (hence, white with cold) to keep the warm blood in the body core from losing too much heat. Presumably the correct remedy once in heat is to allow the reverse to happen, the body to start opening up the blood supply from the inside gradually to the outside.
Both sound like received folk wisdom with no scientific basis. Certainly none that Google can find for me.
Watering plants works, if the conditions are right. Inner Stickler’s link explains how the water must transfer heat in order to freeze, and some of that heat will go to the plants. In the opposite approach smudge pots are used to prevent frost damage to fruit by reducing the amount of heat the fruit can radiate. These techniques are useful for early morning frost conditions, not longer periods of freezing temperatures.
Thanks everyone. Also - once outside temps get below freezing, don’t you have to water your corn 24/7 every day all the time, then?
I imagine, ideally, you’ve harvested the corn before then. In the book, wasn’t it a late cold snap in the spring that would damage the shoots?
That’s what I remember. It was little bitty corn plants, not full grown.
Rubbing frostbitten feet is a no-no. It results in trauma to them. Rubbing snow on frostbitten parts means you’re adding mechanical damage from crystalline material, which is even worse.
LHOP had some dumb ideas.
And the deadline for watering the corn wouldn’t be the first rays of dawn, but “as quickly as possible”. Especially since the coldest temperatures usually come just before sunup.
I recently moved a camellia bush to a new home. I am now told that the buds will die in the spring, because the sun will be on it first thing, while it is still frosty.
By then it’s too late. I doubt they had any means of maintaining a constant spray of warm water on the plants.
Spraying water on citrus is a common method to prevent freeze damage.
The trees are pretty cold-tolerant, but the fruit will be ruined if it freezes, so water is sprayed on the plants, and the latent heat of fusion helps to keep the fruit at 32°F or above. The fruit will not freeze until it is below 32°F, because of the sugar content in it, so keeping it at freezing is OK for a few hours.
What I’m trying to understand is why they thought rubbing snow would help at all in the first place. Frostbitten feet = cold. Snow = cold. How does cold + cold help?
They do the same thing today with oranges if a frost is predicted. It’s a matter of chemistry.
Oranges freeze at a temperature slightly below water (IIRC, 28 degrees Fahrenheit). And water has an interesting property: When you have water at the freezing point, it can’t get any colder until it all freezes. If some is still liquid, it remains as the freezing point (instead of the ice getting colder, the energy will leave the liquid water first). So by spraying oranges with water, and keeping the coating of ice from freezing completely, it will remain just a few degrees too warm for the orange to freeze.
I’d think that corn would behave similarly: the liquid in the kernels would have sugars and starches in it that will lower its freezing point. The “sun’s light” just means you have to do this when it’s dark. Once the sun rises, things will warm up, but it will be too late.
That story reminds me of the time an anti-vaxxer tried to argue that measles isn’t a very bad disease, because there was that episode of The Brady Bunch, where the kids all had it, and they were fine.
You’re confusing the television show with the books. The books, which are classics of children’s literature, are memoirs classified as fiction because Laura Ingalls Wilder changed some chronology of the events in her life and at times combined a few real people into a single character. Farmer Boy, the book the OP refers to, hews closely to the recollections of LIW’s husband, Almanzo, who spent his childhood in upstate New York in the 1860s. The television show borrowed the title, the basic characters, and a few of the incidents in the books, made up the rest, and coated the whole mess with a plasticky, Michael Landon wholesomeness.
The practice of rubbing frostbitten feet with snow was mistaken but a common one at the time. The books merely reflected those beliefs.